Despite what HN seems to think, XMPP is still alive and evolving.
https://snikket.org/ is worth checking out as a (self-)hosted personal chat system.
Re:Google says iMessage is too powerful
by jacob019 on Tuesday January 11, 2022 @08:54PM
(#29901314)
So true, XMPP is fantastic. I also use it for SMS and signal (I wrote some simple bridges for Prosody). We use it for work too. It's great to have it on all my devices. Group chats (MUC) also work well. The modularity is where it really shines. Conversations on Android keeps a long running TCP session open, it works better than push based solutions and is just as light on battery somehow.
I kind of miss XMPP, which seemed like the answer at one point. As it is, I need about six messaging apps (WhatsApp, Facebook Messenger, Signal, Telegram, a Matrix client, Slack, and I'm probably forgetting one) plus SMS/iMessage to keep in touch with everyone.