Trump isn't going to pick someone for VP that is going to threaten his celebrity status. Someone like Nikki Haley, Chris Christi, or some other prominent yet low profile Republican will likely be his pick. Someone who will defend him vigorously but won't take away the limelight by trying to elevate their own status, something MTG and DeSantis would definitely do. Also, the 25th amendment would require the VP and the Cabinet to remove Trump, which won't happen. What's more likely to happen if Trump wins and is also sentenced to prison, is that we will finally find out whether a president is able to issue a pardon to themselves. The governor of Georgia will also issue a pardon to Trump if he is convicted on charges there.