Fluctuating O2 Sats and heart rates.

I can't say much about the O2 levels, but if your heart is not in "Normal Sinus Rhythm" (NSR) it can be hard to get an accurate (meaningful) rate on any instrument. You should have a medical professional do an EKG.

With my family history of Atrial Fibrillation and Atrial Flutter, we would normally see rates that jump around but tend to be higher than normal, not low. Several of the drugstore grade blood pressure cuffs we own have a little icon or text for "IHB" (Irregular HeartBeat) off in the corner, that would light up when we were in an abnormal rhythm. But cheaper instruments aren't smart enough to interpret those irregular beats correctly (or detect weak beats at all) and know whether to count them or not.

The AF/AFl rhythms I mentioned have 3 categories/levels: Paroxysmal (intermittent), persistent, and permanent; the first two meaning it can come and go, and you might need a longer-term recording (Holter monitor) than a simple EKG to catch it,

These may or may not be applicable to you, but you should get them checked out. They can be tied to other problems (O2 sats, stroke, sleep apnea, etc). I'm hoping you have none of those issues, but if you do, that they're caught and treated early!

I will be interested in knowing your outcome. I too have O2 level that drops with exertion. It can be very good (96,97) if I am just sitting around. In cardiac rehab they would alternate with higher and lower exertion to get around it. My Pulmonary function test also showed falling O2 under exertion. I have had two VAT surgeries and my night O2 level dropped each time, and I was sent home with night oxygen until healed. Another factor is my diastolic blood pressure. It tends to read always at the low end.
But none of my doctors have gotten excited about it.

Same here. My O2 is pretty steady, but after three years of LC last week my always low blood pressure has doubled. Led to dizziness and exhaustion, headache, nausea. ER found nothing else wrong. Something seems to going on, especially when my O2 dips a bit at the same time. Anyone else having or had this happen?

I have been suffering the same for about 3 months. For context, I was diagnosed with bronchiectasis with a p. anguerosa infection ten years ago, and was treated successfully with a regimen that included tobramycin. That enabled me to return to work and resume cycling 3000 miles/year. About 3 months ago I started going downhill rapidly and discovered I was now infected with s. maltophilia. More antibiotics and steroids followed but I have not improved. I even went to a cardiologist, and with all the testing everything was fine, but my oxygen levels, which were always 98% or so,, are now around 93% and drop to 88% when exercising. The wheezing and coughing are also more persistent— I have a hard time carrying on a conversation. In March I was averaging 13 mph on the bike, and now I am lucky to do 10 mph, and I stay off many hills I used to ride. I am 6 weeks away from getting results of tests for MAC. I am getting worse. I suggest checking with a cardiologist to rule out heart problems, but don't be surprised if you come away no wiser than you were before. This stuff just needs more study. Hang in there.