I wear one when I go for walks to measure distance and occasionally to monitor my sleep. My one is far from perfect - costing $20 on Aliexpress - but is adequate for what I want. I do not trust its claims to measure blood pressure but it can measure distance walked, sleep (more or less) and time itself ok. I also dont trust the ap that goes with it and I have never used the ap. A potential for monitoring the population goes with these devices if they are internet connected...perhaps they will be required for use of CBDCs!