What is the medical machine called that helps you breath? ?

I’m obese and my lungs were badly damaged thanks to to Covid. Lately it’s been getting harder and harder to breath, and even catch my breath. My respiratory doctor doesn’t seem to want to help me too much except prescribe meds like my primary care doctor. I don’t know what the machine is called I need. The one that aids you getting oxygen. You the thing thing with the tube that has the things that go in your noise. I also think a portable one will help possibly regain my ability to walk. I can’t walk without passing out and causing my lungs to stop working. The little function that is left in them.