Link EPS and Project for UNpublished data in EPPM

Do we know the best way (if possible) to extract the EPS fullpathname for a given project NOT using the pxreporting schema? I have a lot of users still not using publication, so am looking for a workaround that will allow me to build a BI Pub report where the parameter is Project ID and the resulting query displays the EPSHIERARCHY.FULLPATHNAME - but raw from the database rather than relying on the extended schema tables and published data.

I am happy with the available tables, the use of BI, and can easily build it with published data, but cannot find how to do so with unpublished data. I have explored all the DB tables via the dbo user and cant find any key linking project to EPS when the project is not published.