Preferably one that’s popular enough to have more content than a cobweb
If it’s just text, you could always go back to IRC https://en.wikipedia.org/wiki/Internet_Relay_Chat
There’s Matrix, which is federated (diff protocol than ActivityPub, though). It seems decentlly active but atm maybe one of those things where you need to already know people who use it to be able to find the good stuff, because I’m struggling to find much of anything I like (but I’ve also been dodging the larger groups because I’m nervous lmao)
There’s also XMPP or Jabber as it used to be called, which is better for 1-on-1 type conversations, but group chats are also a thing there.
I see, but I don’t think I know anyone who uses it. I know matrix has a public channel, but is the public channel decent? I’m honestly kinda nervous to jump into a new platform-- I’m already nervous enough to post anything on a platform I’m already familiar with
Matrix is quite popular in Europe. German police and army uses it in their private instances…
There are a ton of programming channels that are very active: Rust and NixOS are the ones I follow.
I think the best implementation so far is Beeper, where you have all the bridges to different chats together with Matrix. I run it so I use the same app for Signal, Telegram, Whatsapp and LinkedIn. You can set it up by yourself too, but Beeper makes it very easy. They open to public later this month.