What technical limitations?

I’d guess it was the small battery in the watch. A lot of features on Apple’s smartwatch cause serious battery life problems unless they can be offloaded to your phone at least most of the day.

For example if you have the weather conditions on your watch face… the watch can lookup the weather but it generally will ask your phone to do that. Stuff like that is a lot easier if you control the phone operating system and aren’t just running an app.

… for example if you never launch the weather app on your phone, both Android and iOS will reduce it’s ability to drain the phone’s battery by running in the background. Apple makes an exception to that rule for weather apps where the user has a widget an Apple Watch face. How could the Android battery management systems know what widgets are on your Apple Watch?

The technical limitation of not running iOS I guess.