Thank you! I don't know how I missed the Garmin. (My google-fu is weaker than I had feared.)
TIL: Garmin also uses HRV to infer respiration, aka respiratory sinus arrhythmia. But it's good enough for all day. And skimming their forums suggests their users are content that it works as advertised.
TIL: Garmin also uses HRV to infer respiration, aka respiratory sinus arrhythmia. But it's good enough for all day. And skimming their forums suggests their users are content that it works as advertised.
https://www.garmin.com/en-GB/garmin-technology/health-scienc...
https://www.garmin.com/en-SG/blog/critical-relationship-betw...