Not medical advice, just an anecdote. Regarding helping your lungs recover _after_ quitting smoking. I can't recommend this highly enough.

https://www.amazon.com/dp/B00JWTRA5I?psc=1&ref=ppx_yo2ov_dt_...

I quit smoking years ago and have always felt some residual effects. After a few months of breathing exercises with a muscle oxygen trainer, I've noticed a night and day difference. I spent a few weeks coughing stuff up, my blood pressure has improved, as has my cardio performance on measured performance equipment like the Peloton.

Again, this is just my personal experience, but it might be worth a look if you're working towards a long term recovery.