I’ve started working on a much-needed cleanup of Mac Photos libraries. Deleting duplicates, similars, etc. In a few camp/event-specific libraries, I have Albums and Slideshow projects set up. And I want to keep those as-is. I don’t want to delete any of those photos.
The problem is I am unable to find a way to show me “photos which are unused.” I know I can create a Smart Album of photos not in any Album, but it seems like there is no way to do something similar for Slideshow projects. And I am not able to find anything in the interface which will help me identify, given any specific photo, what albums or slideshows it is a part of.
I welcome any help in my endeavor.