Breath trainer - what device to choose?

Good morning. I am 74 years old and sleep apnea. I lead a sedentary lifestyle and noticed that I have shallow breathing and sometimes I lack air. I was led by Dr. Nastałek Krąków ul . Skawińska. Currently, it is in prokocim, but does not accept because they are a cowid hospital. I plan to purchase a breathing trainer and therefore a question. Is this a good idea and which you possibly recommend. Thank you. With respect Stefan Rzewuski