There's a proposal that would let video encoding be accelerated without going through the entire WebRTC pipeline: https://github.com/WICG/web-codecs/blob/master/explainer.md

Somewhat tangentially related, for cases when P2P connectivity is not needed, there's also a proposal that lets you send data unreliably, but in a client-server setting: https://github.com/WICG/web-transport/blob/master/explainer....

Both are currently being actively prototyped in Chromium (full disclosure: I've been working on the latter).