Create a project page and admin page that enables the project page per project -not to all projects

Hello team
I have been playing the last days with the forge apps and i manage to setup either a project page, or an admin page or other modules,deploy and install them.

What i wanted to do is to make one project page with an admin page that will allow me to enable the app in selected projects(saying the app in reality it is the project page)

I know i can setup one of the templates and then enhance the manifest to include the additinoal module i want
I findit very difficult to understand what the structure should be of the files/project, and what to include in each
Could you please suggest a working solution which will showcase the manifest, and any structure with what files i shuld create and in top level what they should include?
Thanks in advance