What Will No Longer Work after March 31, 2025
Accessing albums and media items not uploaded by your app: The Library API will no longer allow access to the elements in a user’s library that were not uploaded by your app. Instead, you can use the Picker API.
It looks like they're creating a specific way for photo frames to be granted access to shared albums, but the linked page doesn't say how a photo frame developer can get access to that: