I run it as a cron on my NAS, and the only intereaction I need to have with it is to give it a new 2FA code every ~2-3 months. Highly recommend it
[1]: https://github.com/icloud-photos-downloader/icloud_photos_do...
The way I do it is slightly roundabout but works well — I sync to iCloud, which in turn syncs to my desktop, which I backup to my NAS from there.
(Important note: You'll need to turn on "Download Originals to this Mac" in Photo's Settings, otherwise you'll get hi-res proxies rather than bit-for-bit source images.)
https://apps.apple.com/us/app/photobackup-backup-photos-and-...
I recommend everyone who hasn't done it before, to hit the above url while logged in and firing off an export. It will respond back after some time with URLs you can download. Great for downloading your Youtube playlists and history.
I haven't seen any alternatives to Google Photos either. Ente might be most promising, but their iOS app is not great at actually automatically uploading photos.
There are some situations where you may have entered geolocation data on the app/website and this will end up in the json file rather than embedded in the image file metadata. It's up to you to work out how you want to merge this back in.