@medtech4 , I was diagnosed in 2020, as stage 4 right away, with metastasis to the liver. Those early days are a bit of a blur in my memory, but I know I cried a lot, and my husband and I held each other. I wasn't ready to express how I was feeling in words, but we could talk about treatment plans and appointments. It takes me a while to let the heavy stuff sink in. I think he found more comfort in talking with others in his family, his sisters. Just try to lean on each other and understand that all of the feelings are valid. Keep the communication going as much as you can.
We honestly don't know how effective any of our treatments will be, or how many side effects we'll experience. But I do know that there have been significant advancements in lung cancer treatments. Most of that has come from immunotherapy (like what you'll have), and targeted therapies (like what I have). There is real hope in these treatments. The statistics are lagging behind today's reality. I'm part of a support group that is made up of people with different types of stage 4 cancer, who have all been living with these conditions for 5 or more years. There are many people living productive lives with metastatic cancer.

Please join us in the Lung Cancer group. Here are some links that may be helpful.
https://connect.mayoclinic.org/discussion/starting-immunotherapy-keytruda/
https://connect.mayoclinic.org/comment/1165868/

@medtech4 , one more question. Do you know if a full biomarker panel has been run against your tissue samples or blood?
The results can take two weeks because a special lab would run the tests (FoundationOne, Guardant, etc.) The results can help drive treatment decisions.