I'm opting for a skin instead of some kind of additional cover. I've really been liking having a dBrand skin on my Nintendo Switch, so I ordered one for my 12.9" iPad Pro too.
If you look at Federico's Magic Keyboard review here, he does mention that his 2018 model Cover Buddy does not allow the Magic Keyboard to fully close:
magic-keyboard-for-ipad-pro-a-new-breed-of-laptop I have to wonder if they have remedied that now or not.
Also--I know this may sound weird, but I hate the idea of any case/cover that requires me to slide the Pencil off of the side of the iPad rather than just place it there. I know that most people out there aren't as picky as I am about wear and tear, but I do not want the Pencil marking up the side of my iPad and I've seen a lot of them out in the wild that have that issue.
My ideal side protection would be something like the iPhone 4 bumper. I just want someone to give me something like that but way thinner and less obtrusive and that lets me still use the Magic Keyboard.