RE: Business Central Backup and Restore
The database exports you do from BC online can only be used for an on-premise restore.
If you by Azure means that you are running BC Online then new migration to online is needed after on-premise restore.
If you run your on-prem hosted in Azure then you can restore it like it is a local on-prem.
There is no other backup service for Business Central online, Normally you would not need a backup of BC Online because you can go back 30 days to a point in time, given there has not been and upgrade in that period.
But once you have done your db export you can of course backup that file to any backup service you prefer to use.