The advantage of being a local copy is that you will need to manually import the next version of your appstore app. Thereby browsing the release notes and executing a regression test. This becomes less important in your situation where you are yourself the creator of the appstore-app.
If your application is not dependent on your appstore modules, it has no direct reads or writes to it but just calls some microflows, then you can consider to setup your appstore module as a service. Create an application specifically for the apstore module and expose the functions of your appstore module as published services.
Appreciate quick response. Thanks.