All watch vitals checked with pulse oximeter, medical grade blood pressure monitor, and the watch provides ECG, Blood Pressure, Stress Levels, Blood Oxygen, Live Pulse, HRV monitor, the works : r/GalaxyWatch
Galaxy Watch 3 first look: SpO2, ECG, blood pressure, and more! - YouTube
Samsung Galaxy Watch 5 Review | PCMag
Performance evaluation of a wrist-worn reflectance pulse oximeter during sleep - ScienceDirect
Amazon.com: SAMSUNG Galaxy Watch 4 40mm Smartwatch with ECG Monitor Tracker for Health, Fitness, Running, Sleep Cycles, GPS Fall Detection, Bluetooth, US Version, SM-R860NZKAXAA, Black : Electronics