An engine can be dual fuel natural gas and diesel. But it is very expensive and not practical for residential sized units.
I have done it for remote oil field production facilities. But that was a 30MW power plant and the gas had to be compressed to 3,600 psi. They were piston engines, but V18’s and over 31,000 cubic inches. Six 5MW gen-sets; 110 tons apiece.
Not practical in other words.
Interesting - compression ignition natural gas?
Or does it have spark plugs for the NG mode?