Gyroscope & Magnetometer Accuracy

Hello everyone,

I want to implement a golf swing analysis with Garmin watches for an university project. I plan to use the in-built accelerometer and magnetometer to receive data (as I've seen that there's no access to gyroscope data). Before I start programming, I want to evaulate the  accuracy of the data. Unfortunately, I couldn't find any information on the sensors. I'd need data on the parasitic error.

Thus my questions:
What sensors are used in Garmin watches?
Is there a data sheet somewhere that states the parasitic error?

As I assume that there are differences between all the watches, I wanted to beginn with evaluating Garmin Approach S62.

Thanks a lot for your help!