Smart watches other than Apple's work with Apple's phones (I gave the example of Garmin). How is that restricting competition? And even if Apple is restricting

Smart watches other than Apple's work with Apple's phones (I gave the example of Garmin). How is that restricting competition? And even if Apple is restricting competition (by somehow not allowing Garmin and others to work with their phones even though they do...), they're restricting themselves to about 30% of global market share for smart watches since their watches do not work with Android devices. So if they're restricting competition, then they're doing it in a way which limits their ability to capture the larger market with their watches since if anyone makes a decent competitor they can sell it to the billions of people who aren't using Apple's phones. The fact that no one has made a compelling alternative to capture that larger global market that Apple is ignoring seems like an issue with the competitors, not with Apple.