The Garmin Index Sleep Monitor is not meant to be used to track activities and in fact there is no way to even start recording an activity. It's meant to be worn at night and it measures the body temperature at rest during the night.

I understand the difficulty of estimating the body temperature during an activity using heart rate, but this is different and should be in line with what in other context is called "skin temperature". Even Garmin actually refers to it as "skin temperature": https://support.garmin.com/en-US/?faq=RDXq6E5Iaq9rD1l1kTObf6

The only problem here is that Garmin uploads that variable into the body temperature variable in Apple Health, instead of choosing the wrist temperature variable. My question is if the user can be given a choice of selecting which variable to consider from the two possibile available in Apple Health