Your Apple Watch's SpO2 sensor may be better than you thought | Digital Trends
Apple Watch Pulse Oximeter: Accuracy and Utility in Tracking Oxygen Levels - GadgetMates
Pulse oximeter on a smartwatch: What is it, and why does it matter?
How to use the Blood Oxygen app on Apple Watch - Apple Support
Pulse Oximeter vs SpO2 monitor in Smartwatches: Blood Oxygen Track Reliability, Which One Should You Buy in COVID-19 times, Should you rely on smartwatches to measure blood oxygen,