vfio-kvm VS evdev-proxy

I wrote a tool a while back for managing VMs. It does a bit more but it would work for this situation. It will let you use any key or combo for triggering VMs.

I have a project that I wrote and use for managing my passthrough devices that can use an arbitrary hotkey. If you're an arch user, it's in the AUR. I have a new version in the works, but I'll happily help you with using it if you want.

This is the other tool I've seen that claims to do what you want but I've not personally used it https://github.com/dangle/akeydo

evdev would be the traditional way of handling a simple use case. If that's not working for you, or you want more features, I wrote a service called VFIO-KVM that you can try. It has the advantage of also being able to trigger programs (like ddccontrol for changing monitor inputs) when you switch between VMs.

I'm thinking about adding another example that would use the d-bus methods to switch the VM every 10 minutes or so.

Yes, those cards would work. You wouldn't need a hardware KVM either. I've written a small service that handles toggling between a host and a guest. Just one so far, but I'm adding multi-VM functionality because I have pretty much the same setup, although I'm using a small USB external video card for one host.

You've got a few options. I released a project not long ago specifically for this: vfio-kvm. It has a package on the AUR if you use Arch.

If you want to use built-in QEMU functionality, in this repo's README, there is good example on how to change the toggle.