WebRTC video calls have been added to the AngularPwaMessenger project. The back end supports WebSocket connections that are secured by JWT tokens to enable WebRTC signaling. The current browsers support video calls with WebRTC. The Angular front end supports the WebRTC calls and needs to access the camera and the microphone. The browsers need to be able to connect to each other directly and use the server backend to do that. That means that home/company networks that prevent incoming connections prevent the creation of a video call. Installing the PWA on a smartphone does work because no router/firewall stops the connections. For development, a setup with a self-signed certificate is used that enables testing inside a firewalled network.
The Mozilla Development Network has WebRTC documentation. The WebRTC protocol is documented here and the AngularPwaMessenger backend provides a STUN server implementation for the ICE protocol. The signaling and video calls are documented here. The diagrams/code show the creation of the connection for the video call.