All the spark-ignited piston fleet, but not the diesel piston fleet (which cannot use G100UL [nor is it needed for them as diesel is already unleaded]).
In practice: yes; kerosene (Jet-A) and auto diesel are very close compositions, with the former flowing better at low temperatures (as might be found high in the atmosphere). Jet-A comes out of convenient pumps already located on airports.
They’re part of the piston GA fleet for which that fuel is not approved (and neither safe nor needed).