In the beginning minigame of FFPS there is a dark Freddy, that disrupts it, leading into the game proper. I've seem people believe that it's SF, for understandable reasons. I don't believe that it is however, as it's not actually purple, which SF has always been depicted, as well as the fact SF never appears in FFPS. Honestly, I think that it's either foreshadowing Lefty, given the colour, or is just meant to be the opposite colour to the Freddy Sprite we play as.
I don't think the pizza minigame at the beginning of FFPS was canon. Pretty sure it was just Scott trolling. Anyway, the Freddy in the minigame was a more greyish colour rather than Shadow Freddy's dark purple.