This was my question as well. Stadia already does run fully in Chrome, although I realize on iOS, Chrome is basically a shell around Safari's rendering engine.

This was my question as well. Stadia already does run fully in Chrome, although I realize on iOS, Chrome is basically a shell around Safari's rendering engine. Still, PWA seems to be the best path for these services. Stadia's own controller doesn't even need Gamepad API, since the controller can connect directly to the server through wifi, bypassing your phone entirely. Really, it would be no different than watching a livestream on Youtube, which you can control. The only issue is that they use VP9 I believe, which I'm not sure if Safari supports yet.