There are certainly fixed pistol grip M4's out there, but as stated the Urbino is probably a little more practical, as it's a reasonable LOP.
I have very rarely seen the fixed PG models for sale though aside from the desert camo models; the tele-stock is by far the most common one. It works very well when you have a flat cheek piece (made one from fibreglass) instead of that awkward angled one though, no cheek slap!