Somewhat related, but Unreal Engine 5 runs in a browser now using WebGPU, courtesy of a startup. The spacelancers demo is the best performing one, looks visually stunning too. No nanite support yet though, unfortunately:
Looks great but it runs awfully and it's pretty wonky. Yes, the lightning is great, there are tons of rendered objects etc but the controls and camera suck?
https://simplystream.com/demos