Protection between VSAN stretched cluster sites isn't supported with SRM because VSAN is a single vCenter concept and SRM requires two. SRM would support failover between 2 separate VSAN stretched clusters.
vSphere Replication can replicate and failover VMs. Compared with SRM though you are missing:
- Non-disruptive testing (SRM supports testing failovers non-disruptively, this isn't possible with VR on it's own)
- Orchestration/Automation (SRM supports bringing up VMs in a specific order determined by priority groups and dependencies. It uses VMtools to ensure that a VM is fully operational before moving on to the next. VR does not do this. VR would require a manual failover and restart of each VM. This could work for less than 10 VMs, beyond that you would likely run into problems.)
- Failback - SRM will reverse replication and reprotection after failover, VR doesn't have that functionality