(Edited 6/17)
We are in early stages of planning SQL Server 2019 AlwaysOn cluster in Azure. The plan for the cluster topology is the conventional 2 x HA nodes in primary region and 1 x DR node in paired region in the same geography. We don't have experience with Azure Site Recovery (ASR) but we know it can be used for region-to-region replication and recovery. We are wondering if we can use ASR to replicate the two HA nodes from the primary region to the paired region instead of using the single AlwaysOn async DR node per conventional cluster topology. The following Microsoft article shows a graphic of replicating the two HA nodes:
https://azure.microsoft.com/en-us/services/site-recovery/
We aren't sure if ASR is feasible to replace AlwaysOn asynch DR node and what is to be gained. Difference in RTO/RPO? Difference in cost? Difference in effort to set up?