Scenario: Once App1 is migrated to Azure, you must ensure that new data can be written to the app, and the modification of new and existing data is prevented for a period of three years.
As an administrator, you can lock a subscription, resource group, or resource to prevent other users in your organization from accidentally deleting or modifying critical resources. The lock overrides any permissions the user might have.
Reference:
https://docs.microsoft.com/en-us/azure/azure-resource-manager/management/lock-resources

https://docs.microsoft.com/en-us/azure/storage/common/storage-import-export-data-from-blobs
https://docs.microsoft.com/en-us/answers/questions/31113/fastest-method-to-copy-500gb-table-from-on-premise.html

Private Endpoint securely connect to storage accounts from on-premises networks that connect to the VNet using VPN or ExpressRoutes with private-peering.
Private Endpoint also secure your storage account by configuring the storage firewall to block all connections on the public endpoint for the storage service.
https://docs.microsoft.com/en-us/azure/expressroute/expressroute-faqs#microsoft-peering

Reference:
https://docs.microsoft.com/en-us/azure/azure-sql/database/auto-failover-group-overview
https://docs.microsoft.com/en-us/azure/azure-sql/managed-instance/sql-managed-instance-paas-overview

Connectivity can be from an any-to-any (IP VPN) network, a point-to-point Ethernet network, or a virtual cross-connection through a connectivity provider at a co-location facility. ExpressRoute connections do not go over the public Internet. This allows ExpressRoute connections to offer more reliability, faster speeds, lower latencies, and higher security than typical connections over the Internet.
Reference:
https://docs.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-forced-tunneling-rm
https://docs.microsoft.com/en-us/azure/expressroute/expressroute-introduction