I understand the unencrypted and insecure part, so perhaps you are not aware that vnc is capable of running totally secure over ssh
The following use TigerVNC and SSH to create secure desktop sharing on remote localhost only.
It is easy to extend to give more than one user access
I vaguely recall I read that waypipe uses ssh to create the tunnel over which the screen is sent.
waypipe is not remote desktop sharing but having waypipe on both sides enables you to run a specific application on the remote system.
That application will use the remote system’s resources - just a trivial example, you could run dolphin over waypipe - this will allow you to manipulate the file remote system - you even get a built in terminal access by hitting F4.