I have a generall question about the Heart Rate Sensor that is build-in in some phones like the Samsung S9 for example.

I want to make a Fitness App and on one Screen the user should be able to access the heart rate sensor at the back of his phone to get his current Heart Rate.

I have a few Questions on this:

Did someone actually achieve something similar to this? Maybe by only using RN?

Should I go with plain React Native - no expo - because I have to use native Java to acces that feature by what I understood.

On the Java Side of things - do you think it is hard to access this specific sensor and read its data? (Java Noob)