Frankly its possible its already out there but should be very easy to mount such just using a simple Walmart camera.
Other than violating #2 of Cooper's Rules "Never let the muzzle cover anything you are not willing to destroy." I challenge you to find a holster, duty or concealed that will accommodate a pistol attachment. Attaching anything to the muzzle, whether flashlight or camera is begging for an unnecessary death due to a ND.