Create an application that supports both user and administrator

It’s a good idea, nevertheless, and unfortunately, it does not match my use case.

My app need to be public without any authentication required for users (or let’s say visitors). BUT, the admin user(s) of my app need to authenticate.

So what I need to avoid publishing 2 apps for nothing and make deployments a nightmare, is a way, for an app, to have visitors (no authentication) and admin users (authentication).