How does people having the ability to activate alternative app stores on their phones affect you? Or have a Pebble with similar functionality to an Apple Watch?

How does people having the ability to activate alternative app stores on their phones affect you? Or have a Pebble with similar functionality to an Apple Watch? Just don’t activate the App Store or purchase a Pebble and stay in your walled garden. We’re lucky our computers aren’t walled gardens because if Apple knew it would work this well with iOS, MacOS would be the same.