Basic Android shared storage usage
Android Shared Storage Overview.
Note this example is written with android.api == 34. For older apis the permission names are different see.
The example is the unit test for the androidstorage4kivy package, as such it is probably more useful to read than to run. It includes examples of copying to and from shared storage, deleting from shared storage, and using the Android Chooser.
There are two other examples share_send_example and share_receive_example.