How to tell if a SharePoint file is being coauthored?

[carlgrzywacz]

I'm looking for a way to tell if a SharePoint file is actively being coauthored. I don't see any simple ways to achieve this goal. I found the vti_sourcecontrollockid and vti_sourcecontrolmultiuserchkoutby properties in item.FieldValues.MetaInfo but they are not working as expected. The vti_sourcecontrolmultiuserchkoutby property only returns one user even when two users are actively making changes in Office Online. I'd love to add this to PnP if someone can provide some guidance on how to determine if a file is being coauthored or even open in an Office (App/Browser).

Link to a script for testing coauthoring: https://gist.github.com/carlgrzywacz/4909d03c7ab30790fc1777b89dcfd096