It took a lot of work and effort to migrate my ex’s photos off of her iphone and onto an actual hard drive. They funnel the average person into their cloud services with proprietary file extensions, low storage space, the asinine problem of having to have the phone open and unlocked for files to transfer to third party apps, thanks Nextcloud on IOS, and cheap introductory fees.
I’m literally helping my wife with this as we speak. The 1000 photo at a time limit to download from iCloud is pathetic! Google’s solution is SO much better.
Side note - You mentioned Nextcloud… If you’re self hosting, take a look at Immich. It’s a self-hosted Google Photos clone with Android and iOS apps that has very active development and is insanely quick at loading large photo libraries/thumbnails (unlike Nextcloud).