not quite sure what you want to do in thenVM?
You never need a GPU passed to a VM to run any OS in a VM (including Windows) unless you need that VM to be able to access the GPU. You can access the emulated GPU using a browser with the NoVNC support built into UnRaid, or install the Remote Desktop software of your choice into the VM to access it that way. Lower performance than a hardware GPU but enough for lots of use cases.