Hi userbsB15pXNXI hope your day is going well,
To my knowledge Samsung health which is an app on both Samsung mobile devices and galaxy watch active watch 2 track SpO2 levels by simply putting your finger on the fingerprint sensor in order to get a reading this can be seen on both your Samsung phone device and your smart watch device.
I bought the Galaxy Active 2 for the same reason. I found out that Samsung took it off. I am so mad at them!! I talked to a lady from Samsung who said that they were supposed to do an update but when she didn't know. If that helps any. I have been trying to find something with an oximeter but I haven't seen anything in Galaxy store