Migrating OneDrive between two tenants

Hi all,

I am planning a migration of OneDrive for business between two tenants. The how I got pretty much worked out, using either the build in tool in O365 or ShareGate. 

But I am wondering what to about the source OneDrive during migration. It seems like a good idea to somehowe set all users OneDrive to read only or something like that during the migration, but I dont really see any method of doing this from within O365. 

Any ideas on how to do this the smartest way?

Regards