It would be nice to have a more polished version, but haven't played around with it for 5 minutes I can tell you that just gluing together scrcpy and your choice of Xephyr+x11vnc / headless Wayland compositor + wayvnc works surprisingly well. I haven't tried yet since I just wanted to know if it would work at all, but I can't see any reason why you couldn't do the same thing with RDP or even noVNC or Apache Guacamole.