Massive respect to Obi and Fedi for launching such a giant project out of beta!

I am not certain that matrix really is the best freedom technology for messaging.

If Fedi already relies on nostr identities, it would probably be easiest to message over Nostr like with nostr:nprofile1qqsth7fr42fyvpjl3rzqclvm7cwves8l8l8lqedgevhlfnamvgyg78spz3mhxue69uhhyetvv9ujuerpd46hxtnfduq3qamnwvaz7tmwdaehgu3wwa5kuegpz4mhxue69uhk2er9dchxummnw3ezumrpdejqj9swg4 or 0xChat.

And get a readable identifier using NIP5. It would be indistinguishable from the enduser perspective, you could get fault tolerance if every guardian runs a relay so no single matrix server can go down and users could even keep their identity if they leave a federation and move to a new one (just point a new NIP5 to an existing npub)