There is a 3D printed black high impact item from JS Arms https://jsarmsco.com/c9-poly-framed-lower-picatinny-rail-for-laser-or-light/ JS Arms also makes an 6061 Aluminum Picatinny part that replaces the rear sight but it ain't cheap. https://jsarmsco.com/hi-point-pistol-top-picatinny-rail-no-drill-no-tap/
It should be said that you can't affix a rail to the underside of C9 without modifying the frame and covering or damaging the serial number plate. You will have to glue or screw the rail on to attach it.
