I have a dedicated Windows 11 gaming laptop and I'm about at my breaking point of putting another drive in it to test out the games that I care about on Linux. Windows was tolerable to use just for gaming, but the hoops that you have to go through to do some things in Windows are ridiculous. Removing the Game Bar (and stopping Windows from bugging you about it afterwards) is way more difficult than it should be. Also the driver update ping-pong that happens with my Intel video card is maddening. I'll have the driver fully updated and functional, then Windows Update periodically decides to downgrade it to one that's ~2 years old (which breaks stuff.)
If you're using steam, the ProtonDB website [1] has a feature where you can easily hook it up to your Steam account and get a full accounting of your entire collection on one screen.
I don't want to overpromise anything, but ProtonDB is if anything conservative; I find things working better than expected more often than I am disappointed by a listing now. Games with heavy anti-cheat for online multiplayer are often not a good bet, and really old stuff is sometimes not very well supported (although even so, surprisingly well), but Linux gaming quietly snuck up when nobody was looking and one step at a time has become something where I fairly casually just expect games to work in Linux now, without me having to do much more than poke Steam to use Proton manually sometimes.
Single GPU passthrough my solution to any game that requires kernel level anticheat (lmao, no, you're not getting it on my Linux box, silly malware game devs) or does not run under Proton.
Run Linux on the host system all the time, run Windows in a VM only when necessary, and give Windows a GPU only when necessary.
I actually do have two GPUs in my machine, but that wasn't my initial plan when I built this machine. I use the iGPU in my CPU to display my desktop and use my dGPU for Steam under Linux. When I want to run Windows I can unhook the dGPU from Linux, pass it through to Windows, and then both my Linux graphical session and Windows run at the same time. If you have a single GPU then the act of unbinding from Linux it to pass it through to a VM terminates your Linux graphical session (everything not under that graphical session keeps running) until you exit the VM and rebind the GPU to Linux.
As for the second part - yes. Typically you want to export the environment variable DRI_PRIME and set it to the index of the card you want to use to render and it will be displayed on the currently active display card.
The steps might be slightly different if you're using an nVidia card - both of my GPUs are AMD.
