I did not try it, and I am nervous the day I need to - but I think there are some solutions to export photos from the Apple technology stack using open source software [1,2,3].

I remember seeing a longer blogpost re the topic of retroengineering the Apple phot sync story, but I could not find it.

[1] github.com/rcarmo/PhotosExport [2] https://github.com/craigtrim/icloud-photo-export [3] https://icloud-photos-downloader.github.io/icloud_photos_dow...