❄️ freezr ❄️ (npub19sh…fkxd) may I ask what made you discard XMPP?
It looks pretty close to what you seen to be looking for .. except for the fact that it's not a P2P solution to IM ... (although, to be fair, it has to be sai that XMPP is a whole lot more that just an IM .. but that's another story)