Currently, in case we need to override Unity's default AndroidManifest.xml, we simply place our own manifest under Plugins/Android.
For simple uses, this works just fine (and that is great!).
For more advanced uses, this is not enough.
Example use case:
Our game is built for 'Android' target and is distributed both through Google Play and through the Amazon AppStore (Amazon devices are based on Android).
For Amazon, a different manfiest is used, and so we'd like to toggle between different manifests that exist in the project.
If this setting was available through Player settings, i could just keep multiple manifest files, for example:
and just select which one is in use through player settings.