Hi,
what you're asking for is named Fault Tolerance VMs.
AFAIK it's not supported in combination with vSAN stretched Cluster, but I'm happy to get corrected.
As an Fault Tolerance protected VM requires another "shadow" VM which is in sync (Files & Disk, RAM Content, CPU Registers...) that feature does really require a superfast and low latency link between the nodes which would host those paired VMs.
Hope this helps a bit.
Greetings from Germany. (CEST)
