PeerJS still uses a server, it's just that they run one for you so you don't have to set up your own. Using PeerJS from godot would require porting their library and negotiation protocol over. Not impossible, but a fair amount of work.
Ohh, sorry. Yeah, sure. The original webRTC example that my code is based on can do that.https://github.com/godotengine/godot-demo-projects/tree/master/networking/webrtc...