I would keep the iPhone I’ve got until the time comes to replace it, and I would not give them accurate info until then. But I’d never get another, if this is the case.
I have two non-cell iPhones I keep for the home wifi use. One active for calling, but I’m pretty close to going all Landline all the time, myself. My wife and kids never answer me on the phone anyway.
You are not giving Apple anything. The data is for YOU. Why lie to yourself?
Apple doesn't get this information ever. HealthKit is designed to provide YOU information on your self. Apple is not interested in amassing information on its customers. That WOULD make Apple susceptible to the HIPAA laws. They do not want to be under those regulations. . . and as they have said, they are not in the business of collecting customer data.