Due to spending more time in a chair than being active I have a bit more interactions with Gravity than most. :) This has led to fairly significant sleep apnea, which is most easily tracked via monitoring of O2 saturation.

The Apple watch data isn't really useful for this at all as the frequency of monitoring is just too low. There are a bunch of ~$100 devices that you can get from Amazon that do a fantastic job monitoring O2 Sat for a night and have nice integrations into Apple/Android.

I do wish the CPAP's offered this type of integration - that is, they had a Bluetooth receiver to which I could pair an O2 sensor, and have the data coupled with my breathing analysis. This would be nice to have in OSCAR (the open-source analysis package) or even in Apple Health.

Instead, the manufactures like ResMed treat this data as a walled garden and try their hardest to require everything to go through a Sleep Doctor who pays them a non-trivial data subscription.