Azure VMs migration from one tenant to another

I've actually performed this sort of migration: Azure to Azure. I used the Physical or Other option which required spinning up the Replication Appliance VM in the same VNET as the migrating VM. You then need to install the Agents onto the VM that will be migrating. I'd skip the Azure Migrate Appliance/Assessment because you can do a like for like migration.

Heads up: I remember you cannot migrate the Cache disk, just the OS disk. Other than that, this migration is totally possible.  See my attached diagram.  I will confess: Figuring this out in the lab was a pain in the butt.  There's a drop-off in the Migrate Support Documentation because lines start to blur with Azure Site Recovery documentation and terminology.