Proton is good enough these days so there is little reason to use gpu passthrough in a windows vm. The kind of games that don't work on proton are typically online games where the anticheats don't work on linux, and those anticheats typically strict enough to disallow use inside a windows vm anyway. There are exceptions though. For example, I can't seem to run single player campaign of Halo: The Master Chief Collection without crashing after a few minutes on proton despite its gold status in protondb. If I really want to run that game, I guess gpu passthrough is the way to go.
I have a GPU passthrough setup but I hardly used it as I was able to run most of my games in with proton anyway. When I start the VM up it spends so long installing updates I couldn't really use it. I did eventually rig it to download updates and shut itself down in the middle of the night. This involved installing a third party power shell package because somehow Windows has no way to trigger running all updates from the command line by default. Mind blowing considering how obsessed they are with updates.
But based on my experience with my work machine, the whole OS does seem to have it as a design goal that the user be forced to watch the PC reboot and install updates while they sit around twiddling their thumbs. Why else would "Install updates and shutdown" actually shutdown and then start installing updates when you startup again? Maybe they're planning to place ads on the update screen so they wan the user to be there to look at them.
It's probably have something to do with windows' inability to replace files and executables for currently running process, so they'll have to shutdown first and actually applying the updates before those processes launched by the normal startup procedure.
