Depending on the rules and restrictions you want to apply between the different virtual networks hosting VMs of different SAP systems, you should peer those virtual network Note: Virtual network peering enables you to seamlessly connect two or more Virtual Networks in Azure. The virtual networks appear as one for connectivity purposes. The traffic between virtual machines in peered virtual networks uses the Microsoft backbone infrastructure. Like traffic between virtual machines in the same network, traffic is routed through Microsoft's private network only.
Azure supports the following types of peering:
Virtual network peering: Connect virtual networks within the same Azure region.
Global virtual network peering: Connecting virtual networks across Azure regions.
Reference:
https://docs.microsoft.com/en-us/azure/virtual-machines/workloads/sap/hana-network-architecture
https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-peering-overview

A public internet user can reach the SAP Web-Dispatcher over port 443
The SAP Web-Dispatcher can reach the SAP Application server over port 443 The App Subnet accepts traffic on port 443 from 10.0.0.0/24 The SAP Application server sends traffic on port 30015 to the SAP DB server The DB subnet accepts traffic on port 30015 from 10.0.1.0/24.
Public Internet Access is blocked on both App Subnet and DB Subnet.

Reference:
https://azure.microsoft.com/en-in/blog/sap-on-azure-architecture-designing-for-security/

Reference:
https://docs.microsoft.com/en-us/azure/virtual-network/create-vm-accelerated-networking-powershell
https://docs.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/performance-guidelines-best-practices-checklist

Explanation
Scenario: Ensure that all the production databases can withstand the failure of an Azure region.
Note: Use Azure Site Recovery to replicate applications across regions. Azure Site Recovery replicates workloads running on physical and virtual machines from a primary site (either on-premises or in Azure) to a secondary location (in Azure). When an outage occurs at the customer's primary site, a failover can be triggered to quickly return the customer to an operational state. After the primary location is restored, customers can then fail back.
References:
https://docs.microsoft.com/en-us/azure/architecture/resiliency/recovery-loss-azure-region