How you react to the surgery depends on a lot of things, like your age, how extensive a surgery is needed, if you have comorbidities ... It IS major surgery, not to be taken lightly, but for most of us it's a big life-changer for the positive.
You can look online for good descriptions, even videos, of Nissen fundoplication to see what they are going to do. The main thing is have your GI doc recommend a surgeon who has loads of experience, preferably in the thousands and good outcomes.
There are several types of wraps, depending on the results of your tests. I have a weak swallow from having polio, so I had a partial wrap called a Toupet. Most people can swallow past a full wrap.
I had about the worst case because my stomach was stuck halfway into my chest. I am also a senior, so I was in the hospital for 4 days and needed lots of pain meds, but this did keep the pain very tolerable. Some people are sent home the day after surgery, which I would refuse even if I were young, because if there are going to be complications they will come the day after or the next day.
It will take a while after surgery for your lungs to heal, but you should feel lots better for having it.