MNb,
Since Rudolf Spielmann is your idol, I am truly disappointed in you.

You of all people should know the difference between a sacrifice and a combo. If Black accepts the material, he gets killed, and there's lots of blood. If he declines the Knight, he still gets into deep trouble, so it aint a gambit. It's a combination which proves 2...f6 unsound.
Oh, yeah, I know about that guy who surprised Fischer in a simul ( I think he may have gotten away with it twice), but even he didn't take the N. So, it's not a gambit or sac, just a combinational refutation of 2...f6.
Btw, to add to the 1.d4 sac list: There's the Meran, von Henig-Schara, Slav, Bronstein variation of the Saemisch (in which Black sacs a queen in the opening!), Catalan, and on, and on, and on.
And then there are the gambits in the English! Sheesh!