@richardsville, I commend you for inquiring about living organ donation. I can tell that you are very concerned about your sibling, and I want to assure you that your interest along with searching for information has to be a bright spot for him/her. I have no background or knowledge from my experience to share about living lung transplant. This is cedrtainly something that your sibling's doctor and transplant center can discuss with you.

Organ transplant is a complex procedure and comes with benefits and well as risks. The aim of transplant surgery is to provide the best possible outcome for the patient (and donor when there is a living donor). Both physical and mental health are considered when someone is considering being a living donor. I have located the following information from UNOS Transplant Living. This information applies to ALL living organ donors.
"Living donor candidates should be:

In good physical and mental health
At least 18 years old
Be willing to donate: No one should feel that they MUST donate
Be well informed: A good donor candidate has a solid grasp of the risks, benefits, and potential outcomes, both good and bad, for both the donor and recipient
Have a good support system
Transplant program assess the medical and psychosocial health of potential living donors. "
https://transplantliving.org/living-donation/being-a-living-donor/qualifications/
@richardsville, Is your sibling already on the transplant list, or about to be listed? What questions do you have? How can we help you while you walk beside your sibling?

Living with depression is not a reason to be disqualified as a living donor. The donor evaluation team will discuss your history with you. If you have required inpatient care for your depression, it will likely be something that the team will need to explore further. My husband and I were both evaluated as living kidney donors and we brought this up early with the donor evaluation team ourselves. I wish you luck in your effort to donate to your sibling.