I wasn't running Google Drive on my server, but I'll look into the solution of setting the Google Drive --> Google Photos dir as a library in Plex. I am interested to see if altered photos or animations and movies created by the assistant will show up as well.
It wont.... since changes you make to a photo does not sync back to Google Drive :-(
I've also tried the new Backup and Sync app that google released for Google Drive/Google Photos and changes still do not sync to Google Drive's\Google Photos folder.
I've opened an issue with Google on this and I was told it works as designed and changes are not supposed to sync back with no plans to implement it either :-(
if you want your 'edited' files on your local desktop, you have to download (manually) a zip file form google photos web site.