There is a "trailer/cart" thing near Test Track that sells pizza - by the slice, I think. I've never tried it and I do not know if you can get it with your DDP.
No pizza on the menu. Not at Electric Umbrella either.
Italy is missing something by not having a pizza window, even for sucky pizza.
Can always walk out to the Boardwalk and visit the pizza window there, that pizza is slightly better if you don't let it get cold. I don't believe it is available on DDP, though.
They used to have a pasta and pizza place in Future World that I thought was pretty good. I guess they closed it due to lack of interest in the food. The was pretty good. I can't remember the name of the place.