I use an Apple Watch. It regularly (about every 2 weeks) to review who and what data I’m sharing with studies. I can easily opt out again, and the system is opt in only.
No different than the situation with iPhones and Android phones, really. Apple has made their money once you buy the device, and views your personal data as a liability. Google is an ad company that happens to make hardware, and views your data as necessary monetisation potential.
As much as I hate apple products (tho new chips are wild), I got to agree here. I don't know ehat apple does with your data but it does seem to my uninformed eye that they do better than the rest.