There are multiple nuclear footballs; the VP also has one in case that person becomes President in a disaster situation.

All the football contains is some communication equipment and a basic set of nuclear options from which the President can choose.

The main item that the President carries is the "biscuit" - a card which has the codes the President must use to verify his identity when opting for the nuclear option. Trump's codes expired at noon today and Biden's went into effect at noon.