Actually we went through this today and got it recovered.
Like you said, the files exist at the vvol volumes. what we did was to mount those vvol volumes to a Linux server, then find out VASA VM folders and individual vmdk files linked, copies them off, add the VSAS VM back to VC.
We tried to copy the files out via VC datastore browser option, but got permission issue, by going through Linux NFS, we were able to.