On Wednesday, September 16, 2020 at 9:23:34 AM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
This seems to be the year of smart watches adding O2 sensors. Garmin has a whole line of them from $200 to $1200. How does the Apple watch do in direct sunlight as in our cockpits? As a trial I bought an inexpensive smart watch from BangGood which worked fine for reading O2 but was basically unreadable in sunlight.

You can buy a finger pulseoximeter at your local pharmacy for far less than a sport watch, very readable under all light conditions. Fitbit has recently added O2 monitoring while you sleep, not sure how utilitarian that might be.

Walt