Instead of TCP+XML it's HTTP+JSON

The IRC is just a front end. Could use any front end

I see. So more similar to ActivityPub.

I wish them the best of luck. Federated systems struggle to achieve critical mass, and if they do, large corporations tend to snuff it out. I distinctly remember Google committing to The Microsoft EEE strategy with XMPP. We've left behind lots of great ideas in the last 20 years