In apple school manager, under "locations" on the left side. You can add another site. Giving you access to another vpp token to add to mosyle.
After you add the new "site" go to settings then "apps and books", you will have a selection of the new site without any of your apps.
You can transfer apps between sites. or purchase to a specified site.
Meaning you don't have to revoke all your current VPP apps on your current VPP token on your current MDM.
I believe when you switch the token to another MDM it revokes everything at the same time the moment you hit accept on Mosyle, to answer your original question.