Use Pixel watch as Heartrate monitor for phone apps?

I have a Pixel watch and a Samsung S22 Ultra. I want to use the Pixel watch as a heart rate monitor source for an app on my phone.. however, when I try to pick a heart rate source the watch doesn't show up. Every web search I do talks about tracking the activity using a watch app.. but i don't want to do this, because it kills the already abysmal battery life. Is there some way to use the Pixel watch as a connected heart monitor only?