[Both are citizens of Florida. The 12 Amendment to the Constitution would mean that the electors from Florida (a state that Trump will need) would be subject to being disqualified.]
We unfortunately tend to forget that President and Vice-president are two separate offices. Superficial usage, poor understanding of the Constitution due to K12 education and media propaganda makes it seem like voting for Prez is also voting for Vprez.
The electors when confronted with a situation of Prez and Vprez from the same state and the electors represents that state. They can vote for one but not the other. For example in a Trump\DeSantis ticket, Florida electors could vote for Trump for Prez but not for DeSantis for Vprez or DeSantis for Vprez but can’t vote for Trump as Prez. You could end up in a situation where the Prez candidate gets his 270 and the Vprez fails to or vice versa.
If be chooses DeSantis let’s hope they have a contingency plan for that possibility.