I think the biggest thing that stadia is trying to enable is being able to play all games on non-windows systems. You could play a desktop game on your android phone or even on your Chromebook.
My main desktop is dual booted but I never really boot into Linux since I often game, although I really prefer Linux interface+desktop. If Windows could be a kvm guest and GPU passthrough worked I would def go with that option.
edit: I found this which seems to give a good overview but I'm still curious if you have any tips/hacks for getting it working.
Building a rig and just putting Windows 10 on it and installing steam takes about an hour if you have done it before and about 6 hours if you haven’t and have a tutorial. You could just also buy a prebuilt rig for 10 percent more.