Yes. Yes it is. I had a single Windows install that was my main system. I eventually decided to semi-switch to Linux, and passed that SSD through to a VM, along with the GPU and half of my USB ports in order to continue running that Windows install for gaming and Adobe stuff. You just have to keep messing around with the config of the VM, and look up info about getting your UUID from Windows to add to your VM config, so your Windows license/activation will keep working as is. There are guides and info for all of this if you Google around. Don’t remember exactly where I found those guides, as I ran that setup for about year and then switched that Windows install back to bare metal, and it has been about another year since then. I do remember that I got the same boot issues as you when switching back and forth between bare metal and VM, and I had to run the Windows boot repair tools to get everything working. Trying looking into that.