https://www.codexpedia.com/android/android-write-and-read-to-external-file/
Two apps:
- external_storage_write_file
- external_storage_read_file
external_storage_write_file ceates a file with some random content, the file will be deleted on app deletion. external_storage_read_file reads the file created by external_storage_write_file, it requires user to grant the permission to read from external files.