Today Apple announced their new $400 Series 6 Apple Watch will have the ability to monitor blood O2 saturation levels (in addition to other medical features). Valuable medical info not only for pilots but for an early indication of pulmonary changes such as seen with COVID-19 infection.

Not sure if their cheaper SE version will have this capability. At least one prior version had similar pulse oximetry capabilities, but the FDA did not approve of its activation. Uncertain if this feature can now be unlocked for that model.