[Wonderfall]

Unsure why you think the storage access framework doesn't let you grant access to a directory. You can literally try it on a relatively modern app such as Lemuroid: the system file picker lets you grant access to your ROMs folder.

Whole access to the shared storage is deprecated by SAF and scoped storage. That doesn't mean there is no way to achieve the same productivity tasks you could achieve before: it's just that now you're granting explicit fine-grained access to the files and folders your app needs.

MANAGE_EXTERNAL_STORAGE still exists and is now reserved for apps that can justify their file management purpose. Since this is a highly privacy-invasive permission, Play Store requires a review for these kinds of apps.