According to Mathworld there is an undocumented function
GraphComputation`GraphProduct[G1, G2, "Cartesian"]
To compute the cartesian graph product.
Now in line with the example shown:
I would expect
GraphComputation`GraphProduct[PathGraph[Range], PathGraph[Range], "Cartesian"]
Is the function just unfinished (and presumably the reason for its undocumented nature), or is there some way to coax it into providing the correct answer?