So recently we had shared Google's plans to update the Fit app for some new health monitoring features, and it's now out.
There are 2 main new features: it'll read your heart rate with your finger over the rear camera and then it'll read your breathing rate by using front camera.
I didn't realize I HAD the update as the feature is not more front and centre.
You have to scroll through your main screen between some of your other activities to see the option to start the measurement.
So this does work... I didn't compare it to the heart rate monitor on my watch, but I think my watch is easier. And in order to get it to work I did need to make sure the camera's flash was on.
Neat, but unnecessary I think..