The Mastodon instance I’m on has blocked all known Meta IPs as a preventative measure. So I imagine some admins will federate and some won’t, and users will be free to join the instance that they wish to.

Doesn’t work on Jerboa ☹️ At least I now know why my feed seems to be filled with these html image links.

I’d suggest Löve, which uses Lua. It’s a powerful language but equally easy to learn. You could also try Pico8, which is also a version of Lua. It’s presented as if it’s an old 8-bir microcomputer with a built in sprite and tile editor. I find Pico8 much more approachable for beginners. Python is another good starting point for low end hardware.