Per the docs(https://developer.android.com/reference/android/app/backup/BackupAgent#FLAG_DEVICE_TO_DEVICE_TRANSFER https://developer.android.com/reference/andro

Per the docs(https://developer.android.com/reference/android/app/backup/BackupAgent#FLAG_DEVICE_TO_DEVICE_TRANSFER https://developer.android.com/reference/android/app/backup/B...): "The transport is for a device-to-device transfer. There is no third party or intermediate storage. The user's backup data is sent directly to another device over e.g., USB or WiFi."