I have one too. I have worn a Fit Bit since my heart surgery. 68 bpm right now plus it keeps tabs daily giving me min/max averages. I think some of the new ones monitor O2 as well.
Yes... Mine does 02 saturation, stress levels, exercise zones and recovery estimates and sleep analytics.
I'm a geek at the data, and it does help me to improve my choices.....in certain instances. I tend to ignore the "excessive" activity warnings. :rolleyes: