Android APP (using SDK) to share realtime HR from watch

new to this, so asking basic questions if you don't mind.

It shall be possible to make an android app that access regularly (or event triggered) the watch to detect HR values. I wonder if this is possible with the Android SDK and if the watch needs to be equipped with a custom IQ app or can the Android app access the HR sensor programmatically directly ?

Thanks for any thoughts and tips.