Android flow I’ve found(fixed in android 8, working on 7.1.1):
To make app uninstallable by the normal user make the app device administrator, add “android.permission.SYSTEM_ALERT_WINDOW” to the manifest and make sure it’s not granted by the user.
Now when you try to uninstall the app, it tells you to disable it from device administrators but the device administrator disable dialog is System Window handled by the app itself and if the app has this permission but not granted, settings will crash with SecurityException leaving the app untouched.