@markstos@zachleat at least Mastodon has #Brutaldon that can work even in feature phone browsers but I'm not aware of a J2ME app for old feature phones yet (I'm sure it'll be made by someone since Apple II and PalmOS clients exist).
@SpaceLifeForm Caught a #Perl post from @praetor, saw he also recently mentioned #Brutaldon, a low-end-browser compatible #Mastodon web client originally written by @carcosa. Started reading the latter’s posts, and here we are.
Luckily, there's CLI clients like @tut and toot, and maybe #Brutaldon (is that still a thing?)
Edit/P.S.: https://brutaldon.org is still there, but I couldn't get it to work in w3m, links, lynx, or firefox. It might just be an issue with fosstodon (or the newer versions of Mastodon), I don't know.