Altitude sickness, breathing issues at the Grand Canyon and Bryce with

Hi, I’m 78 and I was diagnosed with mild Bronchiectasis in 2019 after a severe bout of pneumonia . I nebulize once daily , never tested positive for MAC and have always had normal spirometry test levels. In January we made plans to travel to the Grand Canyon, Bryce and Zion. I wasn’t too worried about breathing problems and never had any issues when flying. However, I recently had a spirometry test before my appointment with a new Pulmonologist . My spirometry test showed a decline in some of the levels tested. So, he raised the saline from 3% to 6%. I have noticed a difference, my coughing during nebbing is much more productive.
I’m now a bit worried about breathing issues on the trip since the Grand Canyon is at 7000 and Bryce 8000. I don’t plan on doing strenuous hiking. Just walking the flat rims. I’m having a repeat spirometry test next week followed by a video call with the doc and will of course seek his advice. I’m wondering if I should rent a portable oxygen compressor. I’m on Spironolactone for moderate tricuspid valve issues and a beta blocker for occasional SVTs. I cannot take ibuprofen as some have recommended for altitude sickness prevention.
Has anyone visited Bryce and the Grand Canyon? What was it like for you? What precautions did you take?

I have a portable nebulizer and will neb daily. It’s about the same time I switch to new cups so I’m taking the 7 cups that I’m using now and will just toss them as I go and not worry about sterilizing. I may take a few new ones to use at the end of the trip just in case I need extra nebbing and will soak them in Alcohol after using. Have you found doubling up helpful with breathing at higher altitudes?