Backup/Restore would be the way to go, but you would need to change to customer-managed key for TDE to be able to do that.
There is copy/move-facility as described here: https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/database-copy-move-how-to?view=azuresql-mi&tabs=azure-portal. But the last bullet point is disappointing:
You'll need to reconfigure transactional replication, change data capture (CDC), or distributed transactions after you move a database that relies on these features.