Surgeons don't tend to give their patients much information prior to surgery, unfortunately. I've worked on this forum for nearly 3 years, and have seen a wide variety of issues leading to Nissen surgery. There have been quite a few with paraesophageal hernias that were quite large. Generally that surgey is longer, and it's possible that your hospital stay may be extended a bit.
I never recommend any particular eating protocol, because that's an individual call by your surgeon. Still, not every surgeon requires that their patients remain on a liquid diet for a full month. My surgeon didn't think soft foods were all they're cracked up to be either, and can also cause some hold-ups at the wrap site. His opinion is that chewing food to a liquid is preferable.
That said, I wouldn't be a bit surprised that those who have a large paraesophageal hernia will be required to stick to a liquid diet longer, as the procedure is longer and more extensive than the typical hernia, and the recovery is probably a bit more difficult. I would also wonder if you've been told that the surgeon may need to switch to an open procedure. Bill, a moderator here, had an open procedure not long ago and has found the recovery to be pretty similar to the lap procedure.
Actually, your PCP's description of the surgery sounds very close to what they do with every Nissen...just that the large paraesophageal hernia is more difficult to put back in place.
I wish you both the best of luck!
Glad you've joined the forum!