[PaulHoule]

I never use YouTube outside of a browser except on the Meta Quest 3 where you can watch panoramic videos with the app.

A big factor is that carriers get to pick what OS you run on your phone. My understanding is that it was the end of Windows Phone when US carriers said they weren't going to activate any devices.

[JustExAWS]

The carriers don’t care what you run on your phone as long as your phone supports the necessary standards. That use to be an issue with CDMA networks.