3rd party app for HR tracking during activities?

I recently switched to heliostrap from whoop, where I could have an activity going and see the heart rate number big on my phone screen. With the limited in-activity interface of zepp the only big thing I see is the time, I can’t really see the heart rate at the distance I am from my phone. I would also like to preferably have a live notification going where I can see the heart rate on my lock screen during an activity. I have an iphone.

I’m gonna tag this as a feature suggestion because I would love to be able to swipe in the activity interface and just see the HR big right in the zepp app. A live indicator of how much bio charge I’m depleting would also be interesting. But in the meantime, any good 3rd party apps that can do this paired with heliostrap?