Trump is selecting his friends.
This reminds me of an incident in college. We played volleyball certain nights of the week and it was informal where any student can play. Naturally there were good athletes and then those who were not very athletic but wanted to play. When teams were selected it was always the best players first and then on down to worst player being picked last. One night a not very athletic girl wanted to be team captain and when teams were being picked she selected her friends, and among the least athletic. This meant one team was stacked with the best players. When we started the games it was an embarrassment, and not the usual equally competitive games. It wasn't fun for anyone.
My point is that when you want to win you need to pick the best. Trump is picking loyal allies and what appears to be those who are among the least qualified, the most corrupt and controversial. Is he doing it for attention, or just totally oblivious of what he's doing? It's amateur hour. A smooth transition? Good luck. It won't be because Biden is slowing things down, it will be because Trump is a blithering idiot, which 49% of voiters understood a week ago.
When it comes to Cabinet level appointments, a lot of them tend to be political appointees, although the bigger worry here is how it will affect the professionals also in government, such as scientists at NASA, NOAA, and many other Federal agencies where you really do need the best, most qualified people to do these jobs. Most Administrations tended to just leave that alone and do all their political wrangling at the top.
But there may be more internal micromanagement which could cause problems.