How can I create a VM with the root disk being a full /dev/sdX disk?
I would like to setup 3 VMs that have separate disk each from which they boot with Windows Server on them.
You can do incus create --vm --empty some-name to get a VM that’s not based from an image. It will still have a root disk, that’s unavoidable here, but you don’t need to use it.
You can then attach your /dev/sda as a secondary disk with a high boot priority so that it’s used instead of the main root disk.
incus config device add some-name my-disk disk source=/dev/sda boot.priority=10