Ask HN: Best Watch for Tracking Health That Doesn't Share Data

I'm interested in a watch that can help me track health (sleep, etc) which also doesn't report or share data with third parties. I'm a bit Apple-adverse, but open to it if that's the best option. I tried doing my homework on this but am finding a lot of conflicting information and a slew of marketing making it hard to tell fact from fiction. What are your experiences? What device(s) should I check out?