I will once again proselytize for the new pebble time 2 (I am quite a fan of it). Open source and comes with standard sensors for health monitoring (6 axis imu, heart rate monitor, SpO2). Health data can be kept and analyzed on your phone and there are various apps that can do so. Suffice to say there are “surveillance-free” options out there, and if you’re not satisfied with current app options it is easy to hack your own together