The common storage of Android API 31 is not accessible without the picker and that changes the environment for many old apps updating.
A basic problem is that the NDK (25.1.8937393) is not integrated with the Java picker and will hardly be so in the future. So getting the filename from the picker of the general storage and open with fopen() and the new policies will not work.
However fopen() can still be used in the apps own storage.
What to do about it?