Assuming the host Windows OS can access a file share at “\\servername\sharename”, try this command in bash. You will need to be root:
mkdir /mnt/mountedshare
mount -t drvfs '\\servername\sharename' /mnt/mountedshare
The single quotes are important!
Worked for me with a SharePoint Online UNC path. The permissions are screwy though. I can navigate through the folders and see the filenames, but I can’t read files. So need to figure out the permissions thing. Let me know if you get anywhere with that.