Not a very good answer.

If you have a Mac with sufficient storage, you can just enable iCloud to store photos locally, then export them. That could miss some data (I think descriptions you set for a photo were not exported the last time I checked), but it is most of the data.

Do you need to export them? Can you not copy the library file to a different drive?

I didn't answer because it's had and I'd rather not give a incorrect answer.

And, I may have conflated issues: Iphone Storage < Icloud storage vs opposite way.

I seem to remember being able to select all of the photos in iCloud in a browser and clicking download. It zips them and it worked.

I would imagine this doesn't work well after a certain amount of data. I’m also not sure they were the originals.

Yup. Only reason I'm on OneDrive is that they don't mess with photos and their metadata. For now, at least.

I guess it's because the core offering is still some version of "a folder that syncs", and the photo gallery is just a view bolted on top.

I steer clear of any solutions scoped to photos only, as it always turns out they either screw you up by reducing quality and throwing away the originals, or trying to lock you in by only offering metadata they keep in a database they will not let you export.

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...