You’ve titled the post watchOS, but you seem to be talking about IOS features.
For me, it doesn’t matter where they present it, so long as it uses the same data. A separate app implies quicker access to the relevant info from a notification though.
I think most of the features you’re talking about are watchOS.
Vitals is a Watch app. Much like the Medications app, what you do on the watch will connect to the Health app on the iPhone, so there is no new Vitals app for the phone.
Like you, I am very excited about the new fitness features in watchOS (which, obviously involves some things change in iOS too, but is predominantly a feature set aimed at Watch owners, so let’s not get pedantic). I let out a “whoop whoop” when they announced rest days and configurable calorie burning.
If it were possible to load the public beta for any of these features without serious risk to my existing Watch, I would strongly consider it. I am that amped.