Apple Watch gen 6 and later also measures blood oxygen but it says for general fitness only. You may find the document on the Blood Oxygen app interesting. This link is for using the app
and at the bottom of the page is this link for a PDF describing it in more detail
. The Performance Accuracy section is beyond me but I would be curious to know your thoughts.
At first read, I have to say I'm impressed with Apple's efforts to produce a useful blood oxygenation measuring device – and to provide data to demonstrate it's usefulness.
This is not what I've encountered in the past with computer tech companies when they ventured outside their own information tech world and attempted to make devices that could read out medical or physiological conditions from human subjects that might be used in medical monitoring or diagnosis. More often, after they ran into the fortress wall of the US Food and Drug Administration (FDA), they said 'we're not doing all that insane stuff' and ran away, muttering how insulting it was to have their brilliance questioned. People from the pharmaceutical, biotech, and medical lab instrument worlds would often snicker at their naive arrogance.
It looks like Apple contracted a medical device validation company to design the study, collect the data, and do the analysis. Even though it looks like they didn't submit their data and analysis to the FDA for actual clinical device validation, they followed accepted methods. Good for them!
People are usually surprised to learn that the FDA does not have iron-clad standards of just what data is acceptable and what isn't. It's up to the submitting company to convince the FDA that their data is good enough. If there isn't any other such device on the market, Apple's new toy could be considered as state-of-the-art, establishing the standards that any competitor had to meet. Thanks to @Verdinut
I now know that other oximeters are sold, so if Apple wants to sell it as a clinical device, it is up to them to show that their device produces at least as good results as the Withings ScanWatch.
Usual caveat: These are my personal opinions. I do not have professional expertise on instrument validation that it would allow them to be considered widely acceptable for clinical use.