[KronisLV]

I've recently been using a piece of software called RustDesk, which so far feels pretty performant, better than VNC, RDP, TeamViewer, RealVNC etc.: https://rustdesk.com/

You can host a relay inside of a Docker container if you need it as well and it even supports AV1. There's also password auth for each device and permission control.

They have a mobile app too, though I haven't used it as much as the desktop variety, might be worth a shot.