I managed to dd an ext4 img file to the /dev/zdxxx drive and it seemed to work.
However, I had to do it while the VM was running so it was mounted and visible. I’m not sure if this is the correct way to do this, sounds a bit dodgy, wouldn’t using DD when the VM is offline safer?
The problem is I can’t see the /dev/zdxxx device when the VM is shutdown. When I try ZFS mount the .block dataset it failed saying its not applicable.
I was wondering if this is the correct way to go about using a custom .img disk file to replace the (for example) image:debian/buster that I wanted to replace.