I've obtained a recording oximeter, which works well.
But I've had bad Google-luck trying to determine what a proper SPO2 level is while sleeping. Awake, it appears to be nearly always above about 95%; asleep, it runs more in the 93-95% range. I can't even find whether that is normal. I don't think it's considered risky, but I'm still curious.
Also was wondering if there is any way to tell what stage of sleep I'm in from the graphs of SPO2 and pulse rate. Haven't had much Google-luck on "spo2 REM," either.