wish they would work with non apple phones,
or even an apple tablet would be helpful. 
If WOOT would post the MPN we’d know if the blood oxygen app was indeed disabled. Many series 9 new watches are for sale with it not disabled.
I thought about this since buying a series 8 which does have pulse oximetry. When I use my dedicated instrument I get continuous readings. I have another that can record continuously throughout the night if I make the effort, alarms if low, and can review the tracking on my phone the next day.
Why did I even bother to buy into the hype and purchase a series 8? I no longer use the watch.
It still works on my bought-new S9 but is now disabled on my certified refurb S8 (it worked when I first activated it). 
I believe the app was deactivated, in case Apple settles and thus can reactivate. If the device, new or as refurb, left Apple’s hands after a date in January 2024 it is deactivated. If the MPN ends in “LL/A” it was before that date and still active. Hence my comment. Previous WOOT offerings have included the MPN.
I just made this purchase after purchasing the woot Series 7 offer which I’m returning because the battery is dead.
Roughly 80 dollars more than the “New” S7 45mm gps+ cellular, but at least the battery is more likely to sitll be viable and can boot.
s9 Is pretty Good.
It was made After The 2024 cutoff so The Blood Oxygen Is DeActivated.
battery Life 100% still