In modern MTF sex change surgery tissue from the glans is harvested to form a clitoris while leaving the dorsal nerve, (which is connected to the pudental nerve) attached providing a highly sensate and depending on the surgeon, a cosmetically accurate structure.
Being unfamiliar with "nullification" surgery, I can assume this includes a penectomy? The end of that dorsal nerve should still be buried in there somewhere they might be able to find and do something with?
For what it's worth, I had SRS 41½ years ago and an older technique was used. The glans was used to form a pseudo cervix (worthless) and the dorsal nerve was cut. A cosmetic clitoris was formed from left over corpus spongiosum but in my case it died and fell off so I actually don't have a visible one. Upon close examination, I can still see the little remaining hole where it was pulled through but overall, the rest of my vulva looks okay and there are natal women without visible clitorises (clitori?) so it's never bothered me and nobody has ever complained.
I also have enough retained bits of erectile tissue down there somewhere for a feeling of engorgement when aroused that might be problematic if you don't have any, however, apparently the end of my cut dorsal nerve is buried where my clitoris would be if I had one, my libido is healthy and I am still able to achieve orgasm with the proper stimulation. I don't even know how that all works but I'm pretty happy it does!