Does Apple Watch Series 7 track sleep respiration without oximeter?

HI all,

I bought a new Series-7 Watch, but it needs a new battery. For Apple to replace the battery, I need to agree that they will disable the oximeter, due to a patent infringement judgement. I don't currently use a smart watch, and my only reason for getting this one is to gain insight into my sleep and specifically my respiration during sleep. My doctor thinks I have sleep apnea, so I am looking for something to monitor that, without being uncomfortable enough to keep me awake. The Series-7 is the newest Watch that will work with my iPhone 6s. It's not worth it for me to buy a new phone to get a Watch to work.

The PDF describing WatchOS 8 (the version that shipped with the Series-7), says it has sleep respiration rate monitoring.

Would that detect interruptions in breathing while asleep?

Does that feature require the oximeter?

If not, how does it work, accelerometer?

How well does an accelerometer work if I am sleeping on the side I wear the Watch on, in which case the Watch is not accelerating much, if at all.

Thanks,

Scott

[Re-Titled by Moderator]

Original Title: S-7: Sleep respiratory rate if oximeter disabled