This is basically how the WHOOP band works. Anyone with an Apple Watch curious to see can find your tracked HRV in the Health App on your iPhone.
However, looking at heart-rate (HR) itself will be misleading. Big swings in HR or high HR in general usually misinterpreted as having high HRV, when it's often the exact opposite. HRV is a measure of the variability of 1/(inter-beat time). So it's measuring the time-average of really small variations from a set point.
And counterintuitively, HRV is usually highest when the sympathetic (flight or fight) nervous tone and HR is lower. In those situations, the parasympathetic control dominates, and small wiggles caused by "noise on the wire" conducted directly to the heart's pacemaker via the vagus nerve increases HRV. Often times this is when HR is lower, and because higher HR or spikes in HR are often caused by increased sympathetic tone, this leads to a blunting of this "parasympathetic noise".
I track mine on my Apple Watch which records it in the Health App. It's basic graph and I can download it if I want, but I've found tracking day-over-day/week-over-week is a good enough signal. For example, I did dry January this year and practiced meditation every day since and I've seen a step-jump up corresponding to that.
Still have to keep another record of external factors to correlate with it, though. I've heard people finding success with a 3p monitor and the Elite HRV app as well [0].
I've never had the WHOOP, but I use Apple Watch combined with iPhone apps to track heart metrics. I recently discovered AutoSleep and HeartWatch, which both track HRV along with other metrics.
However, looking at heart-rate (HR) itself will be misleading. Big swings in HR or high HR in general usually misinterpreted as having high HRV, when it's often the exact opposite. HRV is a measure of the variability of 1/(inter-beat time). So it's measuring the time-average of really small variations from a set point.
And counterintuitively, HRV is usually highest when the sympathetic (flight or fight) nervous tone and HR is lower. In those situations, the parasympathetic control dominates, and small wiggles caused by "noise on the wire" conducted directly to the heart's pacemaker via the vagus nerve increases HRV. Often times this is when HR is lower, and because higher HR or spikes in HR are often caused by increased sympathetic tone, this leads to a blunting of this "parasympathetic noise".
Source: https://journals.physiology.org/doi/full/10.1152/physiol.000...