The flow is very similar to yours, down to the flashing QR codes! https://youtu.be/rw4f9LfqqpI?t=8
Did you continue to experiment with it? Improve the experience? Try out different approaches?
I lost interest in this approach because it was way more practical to give up on serverless in exchange for only scanning in one direction instead of both ways (e.g., scan a QR code once on mobile to both open the webpage and join a websocket channel, then use it to upgrade to a webrtc connection). It's a neat trick for use cases like AR.js where this is natural to do: https://github.com/jeromeetienne/AR.js