Stockster
Yes, I would say most nissen surgeons are general surgeons. That said, Thoracic, GI, and Bariatric surgeons also do the nissen. These surgeons quite often are also a general surgeons as well.
My nissens have been done by a general, GI, and thoracic surgeon. Thoracic surgeons that I have talk to tend to go through the chest vs belly for this surgery, but that's what they do the most.
Take care,
Bill