I have a Proxmox 6.4 system, on a ZFS RAID 1. Just a single pool, rpool as you mentioned. I'm trying to migrate from spinning rust, to NVME drives. I have just one Windows Server 2016 guest VM. Thank you for the process you outlined above. It appears to work, but I get a weird message during the boot process:

proxmox boot a start job is running for isci in..r or daemon (iscsid)

It delays for a full 90 seconds, and then finishes boot. However, the Windows VM does not start automatically, and will not start.
The message in the task log is:
TASK ERROR:KVM virtualization configured, but not available. Either disable in VM configuration, or enable in BIOS.

Any guidance troubleshooting would be hugely appreciated.