He appears to be picking people from one of three lists:
Republicans with media experience (aka people he knows from TV or social media).
Whoever wrote the relevant section of Project 2025.
People accused of being Russian assets (mostly just Tulsi Gabbard at this point, but there's a reason she's going to be in charge of foreign intelligence and it's not for our benefit).
You're also missing a major part, donorship. These picks aren't incompetence as it looks at first glance. They're deliberately picked for regulatory capture. They're going to burn it down from three inside.
Look at Dr. Oz. He got picked because of his wife's family, the Asplundhs. They're going to fuck up healthcare far worse than you expect.