To measure SPO2, cheap oximeter is better than expensive smartwatch because technology difference
Amazon.com: HEAL FORCE Pediatric Pulse Oximeter Fingertip OX Heart Rate Monitors SpO2 Levels Adjustable Alarm Adult & Infant Blood Oxygen Saturation Monitor With Case : Health & Household
Amazon.com: Pulse oximeter fingertip with Plethysmograph and Perfusion Index, Portable Blood Oxygen Saturation Monitor for Heart Rate and SpO2 Level, O2 Monitor Finger for Oxygen,Pulse Ox,Oximetro,(Red-Orange) : Health & Household
Walgreens Pulse Oximeter with Respiratory Rate | Walgreens
Fingertip Pulse Oximeter$39.99 - A&D Medical
The 6 Best Pulse Oximeters of 2023, Lab-Tested and Expert-Approved