I don't really like discord, but my gaming group have been using it for rpg stuff. Chat channels, video calls and easy to setup bots have all been really useful.
But I get the feeling the enshitification is going to get worse, so I was looking for somewhere else to migrate to. The video stuff isn't as important, we could switch easily to other services. But before I start a new campaign, and spend time setting up bots with routines for rolling dice and calculating tables, I'd like to do it somewhere that isn't in talks for an IPO.
I'm not really up on stuff like this, so I don't know if there's some obvious similar choices or an alternative medium that I haven't considered.
Oh, yeah no activitypub isn't meant for private messaging. It's great for things like mastodon and lemmy, but there is zero privacy, it's meant to blast out to anyone who wants to listen. Messaging the best standards right now are Matrix and XMPP.