I don't see why you couldn't use it as a premade rootfs. You actually don't need to use setup when changing hardware on Windows either. You can push extra drive

I don't see why you couldn't use it as a premade rootfs. You actually don't need to use setup when changing hardware on Windows either. You can push extra drivers for the new hardware using DISM. I've used this method to move a disk to new hardware a few times.