HUAWEI has recently updated its firmware for the HUAWEI WATCH GT2. With this update, it introduces the SpO2 function that was missing on the watch.
SpO2 is an estimation of the Oxygen in the Blood. Under normal circumstances, if you have a low SpO2 percentage count, it may mean that your body is not functioning normally and you may need to seek medical attention.
From Huawei:
About blood oxygen saturation
Blood oxygen saturation (SpO2) is the percentage of haemoglobin (HbO2) in your blood that contains oxygen, and indicates how much oxygen is present in the blood.
Here is a video to show you how it works on a HUAWEI WATCH GT2.
If you did not see this feature, make sure you get the latest update. It should be 1.0.6.32 or higher.
Once updated to the latest version, you can see the function on the watch.
Click on it and it will start measurement. It takes a few seconds to measure. Keep your hand still and let the watch face facing up.
Once it is done, you should be able to see the SpO2 readings. Have fun with the new feature.