Afaik you need some external resource to coordinate the punch. The STUN protocol is purpose built for this, and both clients need to be able to reach a STUN server to coordinate which port and public IP they’ll try to connect to each other on. I assume this does something similar but with p2p network tech instead of a STUN server.

According to this poll, fediverse definitely skews older. There’s some sample bias for whoever is in this guy’s circles, but I think it’s relatively valid.

https://mastodon.art/@jsstaedtler/110668308409683502