There was a W3C draft [1] ~pthatcherg was working on for P2P support for QUIC in the browser that could have maybe become a path to WebRTC using QUIC as a transport, but I think it may have been dropped somewhere along the line to the current WebTransport spec and implementations. (If Peter sees this, I'd love to learn more about how that transpired and what the current status of those ideas might be.)
A more recent IETF individual draft [2] defines a way to do ICE/STUN-like address discovery using an extension to QUIC itself, so maybe that discussion indicates some revived interest in P2P use cases.
I hope P2P stays around in browsers.