Even damaged lungs will benefit from B5, B6 and folate.  REAL folate, not the synthetic folic acid form which can be truly dangerous.

https://www.livestrong.com/article/341529-10-foods-for-healthy-lungs/

Using horehound is a wonderful idea.  Some people don't like the taste (it's like licorice mixed with root beer, kinda).  I like to suck on horehound drops but I can never finish a whole drop because they get quite strong.  If I was fighting a terrible cough or bronchial congestion, however, I could make myself finish a whole candy drop or make myself a cup of tea from the herb itself.  They may now make a horehound tea for purchase, I don't know.

https://www.healthguideinfo.com/herbal-medicine/p26419/

How to cleanse your lungs:

https://www.naturaltherapypages.com.au/article/lung_cleanse