I have used devices such as these. They are inspiratory muscle trainers. They do work but you cannot use them for long because you can hyperventilate. IF you decide to buy one, work with a physiotherapist. You do not want to over breathe.
Yoga, Tai CHI and Qi gong will teach you the best breathing methods and if you practice everyday, you will transform your own breathing. When you breathe correctly, I believe you will change many positive aspects about the body. Strengthening your lungs wil definitely happen. Many people shut down the breathing when they talk, think to much and many other thought processes that we create within ourselves. If you do not breathe correctly many things go wrong. Over time, you can develop chronic conditions. So if you already have a Chronic condition, learning how to breathe correctly is a wise practice. If you are not sure how to breathe corretly, work with a tai chi master or qi gong teacher. there is nothing like working with a teacher compared to watching videos. They can tell you what you are doing wrong.