Here's a name that nobody mentioned (Public Board)
Ron Johnson, Wisconsin Senator
The guy is brash and raises all kinds of hell during Congressional hearings, but he could have helped Trump pick up Wisconsin, one of those toss up states that Trump narrowly lost in 2020.
He's probably too big of a personality for Trump though as Trump was looking for someone to play second fiddle to him.
I would have liked to see Carson as VP but he has his drawbacks of his own (i.e. too calm and in his 70s).