It's only a real "App-Store" if it has arbitrary restrictions and you must pay fees to a company, obviously.

Even with a non-free package, simply add the repository and you're ready to install it.

I think a 'real store' generally allows you to exchange money for something. If I wanted to sell software to Linux users, Steam is probably the closest thing to an 'app store' you could expect to find. Windows has the Microsoft Store, and Macs have the Apple Store.