cabodoc

Interesting idea, but fairly useless as a predictor of Covid infection.  HRV is highly variable within the population- highly correlated with age, but more importantly is highly variable within each individual.  Mine varies from the teens to greater than 50 on any given night and is affected by an infinite number of influences - rest, exercise, sleep, alcohol and who knows what else.  Could probably add corona virus to the list, but would also need to add every other known or unknown infection......
Respiratory rate (measured while in deep sleep) has been shown to be a more sensitive metric - it is remarkably consistent, so any significant rise (e.g. from 15 to 17+) would suggest that something is stressing your body greatly.