Re: Your 1st point. Why do you say to not use WebRTC for web games? The official docs suggest the opposite (link):
WebRTC is implemented in Godot via two main classes WebRTCPeerConnection and WebRTCDataChannel, plus the multiplayer API implementation WebRTCMultiplayer. (...) These classes are available automatically in HTML5, but require an external GDNative plugin on native (non-HTML5) platforms.