The updated procedure is being published now, but basically I believe you should be good to follow the original steps and commands, just use the *.block volume instead of the custom/default_*.
I can confirm this process worked with the updated documentation for VMs/Containers created on 25.04 that are .block files.
I used zfs send | zfs recv to migrate my ZVOL as I had other data on this pool that was functioning as iSCSI targets and I didn’t want to risk any possible issues with that data by taking a snapshot on the entire pool. Once the ZVOl was copied, I was able to create a new VM and select the copied ZVOL for use. The VM booted and everything is functioning as expected.