Not sure: is SPO2 tracking w/ Galaxy Watch 4 still not possible? - Sleep as Android
Cureus | Reliability of Smartphone Applications for the Quantification of Oxygen Saturation
How to measure blood oxygen saturation levels with a Samsung phone using Samsung Health | Android Central
Measure Blood Oxygen Level and Heart Rate on Galaxy Watch | Samsung Developers
Amazon.com: EMAY Bluetooth Pulse Oximeter Fingertip | Blood Oxygen Saturation & Heart Rate Monitor | Compatible with iOS & Android Smartphones : Health & Household
Samsung Health - Apps on Google Play
Samsung finally enables blood pressure monitoring on the Galaxy Watch Active 2; functionality teased for the Galaxy Watch 3 too - NotebookCheck.net News
Note 4 - Oxygen Saturation Accuracy Test (holding my breathe) - YouTube