WatchOS 4 resting heart rate

Is this for all models? I don’t have the features on my S0, but is it confirmed that the S1 and S2 don’t have them either? Could they be S3 exclusive?

Hi, it’s working with series 1, but not series 0. Can confirm by trying it by myself.

This doesn't seem to be a Series 3 exclusive. I can see the area in the Health App where this should populate, but I'm not getting it on my first gen Watch. Oddly, the Cardiogram app does show resting heart rate. Unless the 3rd party app uses a different method of determining resting heart rate, I'm not sure why the Apple heart rate function wouldn't show this as well.