Is there a good app to using Apple watch for HRV alerting?

Quantified Self Apps & Tools
1

I want to track my HRV throughout the day. And ideally, alert on large variance

2

Isn’t the problem low HRV and not high?

3

The Apple Watch isn’t accurate enough for HRV while you are moving, so I believe HRV is only recorded when you use the Breathe app.