Hi HTTPBIS and WEBTRANS,
Yaroslav Romakho and I have put together a new draft for your consideration: https://datatracker.ietf.org/doc/draft-various-httpbis-h3-webtrans/, with help from some anonymous advisors.
Simply put, this draft notes that the WebTransport interface closely matches how HTTP/3 uses QUIC. Running HTTP/3 over WebTransport opens some possibilities to use HTTP in strange and intriguing new arrangements, like running HTTP/3 over TCP (using a TCP-based WebTransport protocol), reversing the HTTP client and server roles, and extending HTTP CONNECT to TCP servers.
This draft operates on top of the existing WebTransport specifications. The proposed protocol is not designed primarily for browser use, so WebTransport's "origin" concept and W3C APIs are largely irrelevant (though still compatible).
We hope to present this work to one or both working groups at the upcoming IETF meeting.
--Ben Schwartz