If? There is no source for this report about Sisi being willing to give up Sinai. It would seem to be unreal, because if he did so, there would be an outcry in Egypt.
Not the whole peninsula. It’s a big place. Possible for a million or so people to wander around in it for forty years. Just an extension from Ghaza Southward along the Med coast. Palis have already rejected it for the usual reason: !. Too much like having a life; and 2. Israelis don’t suffer.