Where I live, you can get 4G simcard with stable 64kB/s speed cap with solid coverage for a price of a small doner kebab, to keep it online it costs a price of a pack of gummies a year, it's a semi-eternal internet. I went for it because I didn't understand the nuance between 512kbits and 512kB/s, 512kbits is 64kB/s, to put it in perspective a 200mb download takes an hour of your entire bandwith. It was quite a bad deal as I later found.

It turns out that because of a quite competetive market between a handful of providers and a good general standard of internet access in my country you can squeeze out a really great deal for almost nothing. Nowadays I am online on a 4G full speed mobile internet with a 500gb datacap with a year to spend it, it cost me as much as a pack of gummies, I have 2 more of those that are not yet activated, so I in reality I have 1500gb to use at a leisurely pace (they expire if not activated by late 2027).
Nevertheless I am stubborn as a mule and computer semi-literate so I want to explore how internet is on 64kB/s in 2025.

Warning

Despite all that will be written here, using 2025 internet with 2002 speeds in fact often gets miserable, not everything can be mitigated, you can only download 2gb with 64kB/s overnight, it's just not enough.
AI models are 10+gb per download, 720p has 3-4 times bigger bitrate than your internet has bandwidth, videocalls won't work (audiocalls might), streaming anything for others is just off the table, some great video content can't be accessed comfortably.
New AAA games can be up to 100gb, old AAA games are still 10gb+, even well repacked indie games often can get over 2gb, legit ways to access games are not flexible enough, only piracy is workable.
Listening to standard-format music online will eat up half of your bandwidth, doubling the (already obscene) loadtimes on everything.
It's not for the faint of heart.

!woof! (\ /\ △△ >\│ ) /// | \ // ╓ ╥ ─^^^^─────ₙ. /// / \// @ /ì ] \_//ⁿ\ ] ▐ \ ] )\┬> ___-\ / )┼ :√ )┼\ │ ^/ :: ^/ :: // :: // :: _// ¡:_// ¡: (_) ♪;_) ♪; (_) (_) a cute doggie to aid you on your journey ! into the world of a really slow internet !

Notes

I would recommend using linux, moreover I would recommend using wayland and I do recommend against using snap, snap is unwieldy and downloads updates unasked/nags you to update, unistalling it is possible and reccomended if you want to use ubuntu. Wayland is needed for waydroid, a fantastic low-resource translation layer (works like an emulator of an android system but 10x faster) for android apps. I use xubuntu which has both snaps, and uses x11 which means there was some scripting and trickery involved in having waydroid run (a weston session that instantly runs waydroid on a script is not that hard but it took few hours to figure out).

Windows is much less malleable and if it decides to send/download some metaanalitics randomly it might be rough, also all android emulators on windows are very resource intensive. It's possible to mark the network you are using as mobile and windows will calm down with using internet willy-nilly and predownloading updates, I tested out some things on 64kB/s on windows and after toggling that option it was ok.
Linux native cli apps like wget, nethogs, apt are also really useful and resiliant to bad internet, I am sure you can get the same functionality on windows but I don't know how.

Other advice I can share after experimenting with such an internet:

Disable all possible auto-updates letting any update start will mean it will functionally disable your internet for god knows how long, !(200mb = 1h)!
Your browser needs to have ublock installed. I'd also recommend disabling all analytics on your browser because it's a pointless waste of bandwidth (even if it's not that much).
- I use firefox with privacy oriented settings toggled in the GUI, disabling analytics and enhanced tracking protection is enough.
- you might install custom user.js like the one SpywareWatchdog reccomends, but it is won't help that much over setting up basic privacy in settings.
- an addon that disables JS/Media on a shortcut might be interesting but I hadn't explored that, if I want to use something in text-only mode I use lynx.
A CLI tool for linux called nethogs is very useful for seeing what "hogs" up your bandwidth.
Waydroid + apk of messenger/discord/social media apps + microg for fixing notification problems + kdeconnect to send notifs to linux + pyclip for shared clipboard
- it's a big 1gb upfront download during the setup, you can download the android enviroment on a different connection and just unpack it on your device,
- I use the no-googleapps version, you can download apks from sites like apkmirror,
- after toggling the "bandwidth mode" included on most of the popular ones, using the internet is pleasant, smartphone apps are the only place in modern computing where those limited bandwidth considerations remain,
DuckDuckGo Lite as a default search engine is really nice, it does not autofill in the search bar but it loads quick and 0 click summaries for things that have a wikipedia article on such a light website are a treat
I really like libredirect, there are (foss) alternative frontends for dozens of social media sites and all are amazing for unusable internet because they have no/minimal JS and therefore are super light, BUT some are very unpractical to use (tent for bandcamp) and for some (anonymousoverflow/proxitok) instances are unstable and work 1/3 of the time, explore your options.
A big find was freetube, an application that lets you comfortably use youtube on poor connection, because of the internet, 360p youtube,
- "legacy" is better optimized than 360p DASH, it does eat up the entire bandwidth, text-only internet only while something is playing but works very reliably,
- it has an option to swap to either audio stream or to a different quality with DASH, in two clicks, lowest bandwidth audio on such an internet is indispensable it can play as you are doing something else online,
- it's advisable to hide "Reccomended Videos" and "Profile Pictures in Comments", in the distraction free settings to make videos start faster,
- freetube breaks once in a while (once per two months or so) because youtube is on a war with alternative frontends, if broken, invidious will probably work, but it is less pleasant to use (audio-only often is autotranslated without a way to disable this "feature"),
Video media piracy is very tricky but there are ways to make it happen, they aren't optimal.

none of the pirated cartoons/shows site that I know of worked in 360p, very rarely (venture bros on wco) a show did play with minimal preloading.
there is a freetube-like app for mobile called newpipe, in a newpipe fork called pipepipe two incredible features got implemented, bilibili/niconico support and a way to force a more optimised codec (less bandwidth for more quality)
bilibili is very lax with copyright and tons of shows with chinese subtitles and original audio (the chinese name of the show can be found on wikipedia) are uploaded onto it and not taken down for months, I even saw some Udemy courses thrown onto there, ofc there are no english subtitles on anime or dubbed cn shows you have to get ready to learn chinese, buddy.
There are some serious QOL issues with this app, so be warned.

it uses fullhd thumbnails in bilibili search which completely overwhelms the network and it can even time out, you can disable thumbnails but the titles are in chinese.
fullscreening in waydroid+weston is somewhat clunky and buggy, fullscreen the weston window on launch and use the built in "window in app" support in android (F11), it somewhat works.
search filters are broken, you can't sort/filter by lenght what you search.

Podcast sites are also fun but none of the podcast sites I seen give you a choice to pick some ultra-low bandwidth stream, same issue with as with most online radios, they work but usually eat up 40-60% of what your internet can do and doing anything practical with the rest is not easy, I found that lowest bitrate on audio-only on freetube is much more managable.
For background music I mostly rock with mod/keygen radios (MODs/XMs are a way music proliferated in the 90s online, before the advent of mp3, they are so small it doesn't use any bandwidth and is a nice spread of chipetune/jungle/oldschool computer music),
- other js players of tracker music are up for consideration but when I looked it was hard to find them, most I found just reconvert music on the server and send you a mp3 stream (same effect as any online-radio audio stream),
Oldschool game music vgmrips/zophar domain is worth exploring, hadn't done that much yet some wiki about game-rip music, game OSTs of fantastic older music have tiny filesizes, 1-5mb are what whole soundtracks are, super tiny! 5mb mp3 is around 2 minutes of music!,
- addons for support of a those formats exist for foobar and audacious has the most popular ones (except of gba/sega saturn/n64) built in, PSX/NDS music can be divine.
It's better for messengers to be used through apks, for social media it depends,
- facebook with a mobile useragent is alright,
- reddit -> redirector addon -> old.reddit is smooth and fun to read,
- halfchan/altchans work fine, not the best place to be but reading them occasionally is fun,
- hackernews also does work smooth (it's reddit for the technically savvy),
annas-archive/libgen
- perfect for epub books
- pdfs are hit or miss, bigger file sized ones need a download manager because shadow libraries tend to have a somewhat weak connection, tried with wget with success.
- You can check shadow libraries status on ShadowLibraryUptimeMonitor
archive.org has a fair amount of fun flashgames and I'd imagine flashpoint would be even better.
- But flashpoint requires a slimming down the selection flash files that install on setup because it will be too big (anything big (200mb+) is NOT feasible to download)
Old school stuff emulation/DOS/Amiga everything up to PSX (or NDS for mobile) are also really tiny (~20mb n64, ~200mb PSX/NDS) and tons of fun, hadn't explored oldschool gaming enough to give all the deets yet.
- A classic site to get all roms for video game consoles,
- When it comes to old software for dos/amiga archive.org has a ton of those.
If internet is ultra occupied by some other stuff you can still look up things online on text-only browser like lynx/w3m and for example scour neocities with it sites are written there by hand so it looks as good as those text-only browsers might allow for.
Tons of text-based content on the internet, dozens of guides and wikis to learn about almost anything are based on text on the web, tons of useful programs also don't get bigger than 200mb, you can find your way around the internet if you try.
RSS (I use and don't like liferea (pc), I use and love feeder (android)) and email clients are from a different era and still work great with terrible internet, combining xitter alternative frontend (nitter) that supports rss and an rss reader is more fun than for you tab, email lists are something that I want to explore.

Musings

Saw a post where someone talked about his internet and how he was using 64kB/s unstable connection and he used a ssh into a VPS for a ssh based webview, Browsh/Carbonyl a headless entire full browser on the VPS scanned the site, converted it to an image preserving the position of the text, the image then got converted to colorful letters and sent over to the ssh terminal, after the whole operation he got a full text terminal tile-view of a browser with letters where letters ought to be, supposedly super fast and comfy on terrible internet, BUT prerequisite is an VPS which is more expensive than fast 4g practically unlimited ""simcard internet"" (using up all bonuses and then discrading a simcard every month) in most countries. He also mentioned about using a VPS to download anything he wanted to watch (for example his youtube subscriptions exported to an RSS) and compress it a lot on the server and then download it overnight or if it's small enough instantly.

Maybe something like that would be feasible but leeching off of google colab resources, depending on what you do google colab without a gpu will let you do 10+ hours of that kind of thing browsh browsing per day, silly. Leeching off of google colab to experiment with medium-sized text AI models through koboldcpp is fun, for people who like it vibecoding through lmarena also might be fun, LLMs of all varieties are on the table but not locally, and I feel dirty after using them for something worthwhile, I do like booting up a short adventure CYOA generated by an LLM here and there.
You are a knight living in the kingdom of Larion. You have a steel longsword and a wooden shield. IYKYK

Considering my parents have a great wifi and I visit them semimonthly, I conciser hooking up a small SAMBA server that I will download stuff into a 64gb unused USB drive I have and swap it every time I'm there with an empty one, idea for sending my big downloads somewhere else. (silly, probably not worth it!)
tor is a cesspool I don't want to go there but sites are optimized there because tor bandwidth is limited by it's private design and routing through handful of servers, for sure there are fun privacy/IT wikis and blogs there (probably not fun enough to risk stumbling across illegal pornography or some gruesome gore)
Torrents are something I didn't explore, should be a very worthwhile on such an intenret, especially torrent-streaming of 360p shows might be something that works neat (i'm iffy on trying because extreme leeching, exlusively downloading, is against the torrents's savoir vivre, seeding will clog up bandwidth).
Considering other untested and silly ideas internet back in the olden days was really slow, in the 2006ish 1-2mbit/s was the higher-end, and something like 512kbit/s (64kB/s) was more standard, it's not like entirety of the old internet vanished, not sure how to access it gainfully.
I read a lot of unicorn jelly a 2002 webcomic on this 64kB/s internet, this site's styling is inspired by it, webcomics will manage the internet constraints really well for the most part, there are also archives of the ultra old internet, like the old text-file archives from bbses and old newsgroup archives to scour, it's all archived online, a lot of interesting discussions happened there but its a wasteland.