I bought this Watch specifically because it had an oxygen sensor, as Samsung removed (bad, really bad move) the HR and O2 sensor from the Note 10+. And now I find out that the 02 sensor is no longer available on the Samsung Galaxy Watch. Samsung claims that in can be done buy measuring Stress level, but it does not show the oxygen saturation level. I'm really disappointed with Samsung.
If you want to go through the hoops of downloading your information from the SHealth app, and looking though the files, you'll find the actual SPO2 measurements there. Just look for files with "Stress" in the name. I'm sure if I knew enough about database management, I could write something to pull out those figures.