I run a qemu/KVM setup in which I have different VMs for different use cases/profiles. Very similar in theory to something like Qubes OS. So far when I want to swap to another VM I have to first un-fullscreen, then click the other VM display window and fullscreen that. I was beginning to work on hotkeys and scripts to allow switching between VMs by assigning Ctrl+NumPad# to specific VMs and then having the triggered VM appear in full screen. But I'm imagining there's probably already a VM display manager that streamlines this.

Does anybody have any suggestions?

The biggest factor is that the display needs to be responsive as I'm using these VMs for daily tasks.

Bonus points if the display manager can output a variable for the currently focused VM so I can script the keyboard backlight to change to an assigned color as well as change the power profile of the base operating system to match the currently highlighted VM better.