Sorry for the long absence from the thread.
I guess a VM would need to be identified as requiring to be backup up
Not sure what you a referring to as VM, so I'll try to paraphrase what you've said.
As I get it, a simplified model of the use case would be the following:
Physical Linux host with a container running on it. Any persistent data that is produced by the container is kept on NFS share which is not connected to the host. You want to backup the data that resides on the share. Also I assume that there is not much of concurrent access to the same files on the share since each container uses its own file. Is everything correct? What version of NFS is used?
Also the part about Windows workload is not quite clear, would you elaborate please?