Rhet Turnbull on Github describes OSXPhotos this way:
Python app to export pictures and associated metadata from Apple Photos on macOS. Also includes a package to provide programmatic access to the Photos library, pictures, and metadata.
I'm planning to use this to pull the Faces metadata out of Photos.app and use machine tags to add keywords to the files themselves. It is the missing piece to my current workflow. If it can also pull out the keywords that Photos' Machine Learning attributes to the images (animals, objects, color, etc.) then I may pull those as well.
/via Roel Groeneveld.