As a kid I played trumpet, one my CF brothers sang in choir, and the other played saxophone. I don't suppose these would replace nebs or ACT but they do make an enjoyable supplement. There is a lot to be learned about breathing by playing a wind instrument. With the air moving and vibrations how could it not help? Plus making music feels good mentally (which is an often overlooked part of CF treatment).
Now I supplement a little with yoga and exercise. Again the breathing control learned with yoga feels similar to active cycle breathing. I'm sure you could add a huff cough to yoga and get some amount of clearance.