I loved my Apple Watch at first but due to exactly these sort of distractions no longer wear it and have more recently turned off most of the notifications on my phone. I am sick of my attention being stolen away by everything around me.
I do wear it for workouts, but once it's closer to end of life will replace it with something dedicated for workouts like a Garmin that holds a charge for 14+ days.
Check out the Quantified Scientist on YouTube, he does some interesting testing on health devices.
But as you say the always-on ECG of a strap like Polar H10 always going to provide a superior result.