This is the answer you're looking for OP. A sleep study only captures one night under one set of conditions. It's useful for catching and setting up treatment for moderate to severe apnea (where your result is unambiguous). It's not great for evaluating borderline cases where a dozen random variables could affect your airways and may deviate between where the study is conducted VS your own bed VS a hotel bed.
Plus with your own ring you can evaluate if side sleeping might be necessary or if you can even get away with back sleeping without your machine and how the two positions might compare.
If you still suffer from mild OSA, you could also consider trying a dental appliance (either custom from your dentist or self-fit from a cheap Amazon kit) to see if that might be sufficient to resolve your OSA. There are some minor jaw issues that can come with that, but it's possible you could use the CPAP at home and take the dental appliance with you on trips (since it's much more portable), if it's sufficient to resolve your current degree of sleep apnea.
Lastly, there are some people who have perfected stomach sleeping positions and found their own custom stomach positions are sufficient to resolve their current degree of OSA. That's a little more complex than I care to explain here, but if you search a bit on OSA forums you'll likely find what I'm talking about described more thoroughly.
And, obviously, regardless of what the pulse oximeter says, how you feel the next morning is a critical variable too, but I wouldn't base my decision on how you feel alone, since one can often cope with mild sleep apnea and still be experiencing negative health effects from it without "feeling" it the next day.
