Not quite
Hi Lee
Not NTR fuel elements are suitable for every kind of working fluid available - and it will be liquefied in the tanks not gaseous.
Different planets require different capabilities and supply different fluids. An NTR that is optimised for deep space will be quite distinct from one designed for planet touch downs - different power levels, different thrust, probably electrical conversion equipment on one, probably gas pumps and piping on the other.
Standard, go-anywhere rockets are an SF mainstay, but quite unrealistic and no economic advantage.
Adam