Anyone have a good resource on understanding the policies that govern the ownership and handling of data collected by an Apple Watch? I quite like that they can

Anyone have a good resource on understanding the policies that govern the ownership and handling of data collected by an Apple Watch? I quite like that they can be used for tracking sleep, heart rate, and many other health-related items. Ideally, I'd have full control over how these valuable, longitudinal datasets I generate are handled and used. But I'm skeptical that's anywhere near the case.