Not sure but I think they can be from the same state.
It’s not done because it’s good to have the top two from different regions of the country.
The constitution states that presidential electors cannot vote for both a presidential and vice-presidential candidate from the same state as themselves.
That is why people often say, that a president and a vice-president must come from different states.
But it’s an easily fixable problem. Trump would simply relocate his official residence to New York, if Trump and DeSantis were on the same presidential ticket as president and VP nominees.
In 2000, Dick Cheney was living in Texas, and relocated his official residence back to Wyoming, to run with George W. Bush as his VP nominee. So this is not a huge problem to take care of , if necessary.