what if..  forget about STUN for a second, it isn't gonna work for most peers (esp mobile carrier networks).  You could support ipv* by 'relays' running coturn and forcing the use of the turn server vs. stun would not expose IP info between the peers.  Coturn has all the stun options, so if a peer was willing, they could opt in to the IP disclosure and achieve a true P2P connection.

multi hops could also be implemented, by using wireguard networks with relays being a 'hop' server.

https://github.com/coturn/coturn