Hi! I've never heard of Expand-a-Lung. It's a good idea to talk with your doctor before trying anything new, just to make sure it's safe for you.
As for incentive spirometers like South Paw mentioned, these are extremely common tools for improving lung fitness. Even people without COPD have used them while recovering from surgery or infection.
There is another common device for managing mucus and lung health called a flutter valve. We have a good article about them here:
https://copd.net/clinical/flutter-valves-acapellas
All of these are available relatively cheaply online, or you can ask your doctor to prescribe them if you want to submit it through your insurance.
Let us know if you end up trying any of these! -Melissa, team member