Storage Scopes? With stock Android you assign access to folders: Documents Downloads DCIM ... storage Scopes allows to limit the access of an App to individual files that you select. iOS comes with a similar access system. But you can enable/disable storage scopes in graphene preferencesn on an individual app base.
Storage scopes is built into graphene os. Apps should not be able to see it, unless they try to cirumvent the permissions assigned to them.