It’s in beta, but it’s already quite usable. You can try it without account on a public instance e.g. at call.element.io

Nice explanation =). I am not OP but I am curious about one point: you seem to have the reverse proxy on your homeserver, not on the VPS.

Is wireguard enough then to tunnel HTTPS traffic to your reverse proxy? Or do you need a more sophiscated tunnel (e.g. ngrok, boringproxy).

P.S. I actually assumed that your VPN entry point is a VPS with a public, static IP. Therefore I understood that your were talking about two servers: the home server with the reverse proxy and a VPS as wireguard entry point. Please correct if this is wrong.