Polaroid does supply material for their 20X24 camera.
Additionally, Polaroid also supplies 20X30 material for Joachim Knill's homebuilt camera. (View Camera Sept/Oct 2002)
Knill typically uses 8 inch (200 mm) and 12 inch (300 mm) process lenses on his camera. Now that is some serious wide angle considering that 37.5 inches or 952 mm would be a normal focal length for that format.