I recently saw a graphic of a physical therapy technique called postural drainage that could be used on COVID-19 patients. It apparently used to be used often before ventilators became widely used. I don’t have enough information to recommend it or not. BUT! It’s all inversions!
Most people think of headstand and shoulderstand as the yoga inversions. And many people aren’t able or willing to do them at home without the help of a teacher. That’s OK. Here are a few that are more accessible.

Adho Mukha Svanasana (downward-facing dog)

Prasarita Padottanasana (wide angle standing forward bend)

Viparita Karani (legs up the wall)
These images are highly stylized, of course. Here are a few modifications. Think of these as restorative opening poses, not stretching active poses, if you are doing them for the benefit of your lungs.
- In downward facing dog, you can put a support under your head and/or your hands. You could even put a pillow or bolster on a chair to support your hips (much as we do in the studio with ropes around our hips).
- In wide angle forward bend, you can put a bolster, blanket, or blocks under your head.
- In legs up the wall, you do not have to be smack up next to the wall. As long as your knees are straight, you can be away from the wall at an angle and still get the full benefit of the pose.