Vivosmart 4 PulseOx is crippleware

I don't agree. Four hours of continuous sampling every night provides sufficient info to determine if the wearer has a problem (e.g. sleep apnea). Spot readings during the day are as good as a fingertip device. I'm guessing that the readings are not continuous over 24 hours in order to conserve battery life.

1) It is not what was advertised (At least nowhere obvious). It’s an ideal form factor, and seems to be pretty accurate compared to my fingertip monitor, but not sure I would have bought it if I had a clear idea of the limitations.  Still debating returning it, but I would so love to see a firmware update to make it actually work.

2) I’m not apnic (been tested), but go thru heavy bouts of snoring at times during the night.  Want to monitor and see if anything changes.  Ain’t worth squat if it won’t record those times.

3) Daytime spot checking is near useless - it takes quite a bit longer than a fingertip clip due to the technology used, the time varies, then flashes the result on the (small) screen for about a second then disappears.  Rather challenging to see unless you are sitting on the couch staring at it.  And it does not record it.

4) I want to use it to monitor my SpO2 during daytime activities - hiking, biking, hill climbing, fitness, etc.  Needs continuous monitoring.  And the battery seems to last plenty of time - after 4 days with 4 hours / night, I still have 50% battery.

5) They had to go to extra work, and implement code specifically to prevent you from fully utilizing it.  It would have been easier from a software perspective to just let us use the sensor same as any other.  They had to put effort into purposely crippling it.

I have to admit, when I was shopping for a fitness tracker, SpO2 was a deciding factor including being able to log SpO2 data to Apple Health. I do feel let down here, and I agree it feels totally arbitrary. They have plenty of fine print about it not being a medical device etc. (and fair enough) but it should be no different to the HR sensor. Living with a chronic respiratory illness, I wanted to have some idea what my oxygen saturation are doing through the day and night.

A sleep study doesn't end after 4 hours.

I agree that one should be able to customize SpO2 settings, but my biggest disappointment was accuracy. I don't have medical-grade gadgets for comparison, but I am contact with someone who studies SpO2 in athletes. This person insists that these devices are garbage. I set out to prove him wrong, but he won. 

I took readings in triplicate at all times of the day. Garmin SpO2 was consistent within triplicates, but it would vary throughout the day with no pattern. When my mid-priced fingertip device arrived, did a bunch of comparison testing and concluded that the Vivosmart 4 was making up numbers. Values varied from 89-96% on the Garmin but stayed 98-99% on the fingertip device. The expert says that SpO2 should stay up near  98-99% and should not vary in a reasonably healthy fit person. If it were just low, I could apply a simple correction (add 5 or whatever), but variability made it impossible to use the data. What is this good for anyway? I was thinking of monitoring for Covid-19, but I think I'd know something was wrong long before SpO2 numbers dropped below the Garmin's usual range. I have not had a chance to go to altitude. 

"Overnight" SpO2 was not useful either. There were substantial dips, possibly related to rolling over on my arm. Sleep tracking in general is better than my older Garmin wearables. 

Will be gifting the Vivosmart 4 and going back to my Vivosmart HR. Would not recommend upgrading for SpO2. 

I've been suspicious of my overnight pulse ox readings for some time. So lately I've been wearing my wife's Vivosmart 4 as well -- same wrist, side by side, above wrist bone. The average reading reported for overnight averages 4 points higher on hers than on mine and every reading on hers is higher than on mine. For pulse ox, 4 points is a HUGE difference. Wearing my device, I have a pulse ox problem overnight; wearing hers, I don't. I don't know which to believe.

Do you see Spo2 variation throughout the night? And is is the same pattern on both watches if you wear them on different arms?

like UK I see dips from 98 down to 85-80%. I also suspect It is me lying om my arm that causes the dips. I read the amplitude of the changes is more important than the absolute value. 

i also found it to be about 5-10 points too low every time i check against two other finger ox sensors. i wish there was a way to calibrate the Garmin Pulse Ox if a firmware update won't fix.