You can actually integrate with Health while still also showing it in your app. Health is like a database of sorts which you can choose to add your data to or access from yoUr app. (Similar to HomeKit, actually.)
Also, to counter one of your arguments above, Apple Health doesn't do a lot of analysis on third party data short of showing it in charts, so there is still value to using Whoops app for that aspect of it.
As an example, my scale is Whithings, my bed had a Beautyrest Sleeptracker both of these services consume and contribute to Apple Health.