@Dev Thanks for posting in our Q&A. From your description, did you mean that you want to migrate the devices from an old tenant to a new tenant? If there is anything misunderstanding, please correct me.
The most important thing is to remove the device from the old tenant and re-enroll the device to the new tanent. Based on my understanding, factory reset is not a necessary operation. If you want the device to be a completely new device, of course you can perform factory reset action.
Hope it will give you some ideas.
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