There's a fairly far a long draft for replacing webrtc's SCTP with QUIC for doing p2p work. It doesn't seem to have any of these challenges, seems to be perfectly viable there for connecting peers. https://github.com/w3c/p2p-webtransport
Alas alas, basically stalled out, afaik no implementation. I wish Microsoft (the spec author) or someone would pick this back up.
WebRTC wraps SCTP in DTLS, so the "great challenge of encryption" has never been a problem there.
It just uses self-signed certificates, which is maybe conceptually slightly clunky compared to "pure" anonymous TOFU, but allows reusing existing stacks.
Alas alas, basically stalled out, afaik no implementation. I wish Microsoft (the spec author) or someone would pick this back up.