I know that that’s partially implemented with the limited photo access now, but it’s confusing from a UI perspective and I don’t understand why this isn’t the default.
The only apps that need full access to my camera roll, are apps like Google Photos, Nextcloud or Immich. Everyone else can suck a lemon.
Absolutely not. Saving a photo does not need the full permissions. If an app does that, the developer is either ignorant or malicious. I see multiple apps that only have "Add Photos Only" permission including apps like Duolingo that.
Similarly the use case of allowing the user to pick one photo doesn't require any permissions at all. Just use the system photo picker. I post reviews with photos regularly on Google Maps and the Google Maps app doesn't have any photo permissions.