A new killer feature for GrapheneOS: Storage Scopes. Ever wondered why an app asked for invasive files/media access without really needing it?
While modern apps rely on scoped storage + SAF, most legacy apps have an invasive approach, and even modern apps can misuse permissions.
User profiles were already a powerful to compartmentalize apps further. The same app sandbox rules apply, but you didn't have to fear granting such invasive permissions on a profile w/o your data on it and w/ different encryption keys.
Powerful, but sometimes cumbersome.
Enter Storage Scopes! When you enable the feature for a given app, it will think it has the necessary access to files/media, but it only has access to its own, well, storage scope. Furthermore, you can manually add directories/files access with the system picker, much like SAF.
Here's an example: Tachiyomi is a popular manga reader app with offline features that need the invasive WRITE_EXTERNAL_STORAGE permission. It doesn't need that obviously, and should use scoped storage features + SAF. This isn't a problem with Storage Scopes. :)