PULSE OX READINGS OF GARMIN FENIX 6X IS 5% UNDER REALITY

I feel really disapointed on 2 problems with Pulse OX Oximeter

1. There is a huge difference between the fenix and the reality. The fenix is 5% lower than real 

2. I bought the watch with ox meter in order to control better my ox saturation. And ot wpuld be very interesting to be able to activate an alarm in case of low ox meter, which would have to be able to modificate. For example, for me on a real and correct measurement I would like to have an alarm if I'm below 92% for more than 1 hour.

GARMIN: FIX OX PULSE