I understand you are wanting to move an AVD VM from one tenant to another. Please let me know if I misunderstanding.
The method you have mentioned is the preferred method. While it is possible to migrate the VM to another subscription then move a subscription to another tenant this is more tedious.
Your method should work, you will also need to create and associate the VM to the host poll. Please see this previous Q&A thread for details on how this can be accomplished.
Hope this helps! Let me know if you run into any issues or have further questions.
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