I just read through the entire thread, hopeful that I'd hear the good news that your husband is on the mend, Cindy Blue. I'm so glad that's the case. Like many others who've commented, we know dozens of people (including some family members) who've had the virus and recovered without complications. And several of them had co-morbidity risks. Despite what you hear from the media, there is every reason to be optimistic even if you get a positive test.
In 2010, I was diagnosed with a chronic lung condition, NSIP-the least virulent of all the fibrotic lung diseases (and no, I've never smoked), so an oximeter is my friend. If you get a low reading (anything under 92) try a different finger. That can also make a difference sometimes, as well as rubbing your hands together before you take a reading. Cold fingers lead to low numbers. Controlled breathing (In for 4 counts, hold 4 counts, release for 4 counts) can bring your O2 saturation up as well. Change your posture for better breathing. It helps whether your Covid positive or not. Oxygen is your friend!
I have had an all time low O2 sat of 73 once when I was flying. It feels terrible. I could almost hear my brain cells dying. But I quickly fired up my portable O2 concentrator and was back in the mid 90's within a minute or two. Now I know that flying even in a pressurized cabin is the same as being at 8000 ft elevation, 10,000 ft for longer international flights. For most people, this is no problem, particularly while remaining seated, but I need a little help at that elevation.
The danger of low oxygen is that your organs will be damaged from lack of proper oxygenation, most notably your brain and your heart. But that is a long term deterioration, not something that happens with one dip.
I think the thing for all of us to keep in mind, whether it's covid or the flu or the common cold is to protect your airway and do all you can to keep the gunk from creeping into your lungs.
We're off to sing in our very abbreviated Christmas cantata this morning, all masked and distanced and only 10 singers. I know, I know, singing is supposed to be bad, but I'm a classically trained soprano. I'm more afraid of not living than I am of dying. If this is my last Christmas on earth, I'm not going to go through it without popping off a few high notes!
Wishing you all good health!