Regarding medications, it's basically a risk benefit calculation as all medications have risks. Perhaps you could take a short term (2-4 week) PPI to see if it makes a difference in your cough/sputum. People who can go off a PPI are those who eliminate all triggers and pay close attention to eating alkaline food. In other words, they eliminate acidic foods. I am not that person. That is some serious time and work to figure out. Plus I have a husband to feed!

COPD includes chronic bronchitis and emphysema. Bronchiectasis is not considered COPD, nor is asthma. My understanding is that one is considered to have COPD if the FEV₁ / FVC ratio is less than 70. Many people's spirometry changes throughout the year, sometimes improved sometimes worse, so take the ratio of 70 with a grain of salt and have a discussion with your doctor.

Do you know about the Bronchiectasis Toolkit? It was created in Australia! Maybe you could contact them for info on doctors who treat bronchiectasis and MAC. There's also NTM.org to check out.
https://bronchiectasis.com.au