Yes you can. We pre-seed from disks, not VMs.
Therefore, what you need to do is:
First deploy the Veeam replicated VMs which means failover/restore in Veeam (it wasn’t clear from the question whether the “Veeam replicated VMs” are already VMs or if they are just in the Veeam backup repository)
After you have actual VMs, you need to remove the VMs, but keep their disks. One way to do it is go the “edit settings” in VMware, remove all of the disks from the VM without deleting them, and later delete that VM which no longer has disks.
Now you can pre-seed from these VMs
I have just seeded with Veeam restores and it worked a treat.
I restored the whole VM rather than VMDK’s to the DR site which allowed me to choose the DR proxy for faster restores.
I then removed the restored VM from the inventory in the vsphere client
then created a VPG in Zerto which took the VMDK’s from the VM folder
then browsed the datastore and deleted the restored VM folder name as the VMDK were now under the VRA
works a treat