Android 10 lacking external storage permission (dirty workaround possible)

On Android 10 Google changed storage permisson. When currently microG GmsCore is a system app (as required for uNlp to work) it doesn't get storage permission (grant permission UI not showing up).

The workaround is to re-install microG GsmCore as user-app (additionally to the system app) and then the grant permission UI does show up and everything's fine. This happens to all non-Android-10 optimized apps, when installed as system apps, so microG aswell.

From the Log:

10-05 20:33:43.204  3302  3302 V GrantPermissionsActivity: Permission grant result requestId=8029825996842873056 callingUid=10103 callingPackage=com.google.android.gms permission=android.permission.WRITE_EXTERNAL_STORAGE isImplicit=false result=1

10-05 20:33:43.204  3302  3302 V GrantPermissionsActivity: Permission grant result requestId=8029825996842873056 callingUid=10103 callingPackage=com.google.android.gms permission=android.permission.READ_EXTERNAL_STORAGE isImplicit=true result=1

Also the text in the settings regarding that permission is somehow strange, contains android.permission-group.UNDEFINED. See Screenshot: https://www.nanolx.org/uG-Android-10.png

Reproduce the issue on Android 10 with microG GmsCore installed as a system app, using the permission behavior, log excerpt, and settings screenshot described here. Trace the storage-permission request and its Android 10 settings presentation; done means system-installed microG receives the needed storage permission and the settings text no longer shows android.permission-group.UNDEFINED.