First, I second the fact that cis women have very little internal sensation. (Current theory is that the "vaginal orgasm" is because the roots of the clitoris run much deeper than the surface and surround much of the vaginal opening - so it's possible to stimulate the clitoris from the inside, as well.) Secondly, unfortunately, sensation requires nerves... if those were discarded in the original operation, they cannot be regained.
Thirdly, cis women who report a G-spot are likely experiencing stimulation of what some doctors now call the "female prostate"; it's the same gland with the same functions, but underdeveloped. Since the prostate is located in a spot that makes removal very fiddly and risky, most GRS surgeons do leave it in place (so it's not so much that they "create" a G-spot as that they don't mess with the prostate, and again, that's most of them doing this), and that place is equivalent vaginally to the cis G-spot. So the prostate *is* the G-spot for us post-op women, literally and technically. (It should also only be about an inch or so inside, so anyone with merely about that much depth ought to be able to find it.)
