I'd have to add one thing about DeBoer's system, the lack of a power running game and physicality on offense is a major issue as far as I'm concerned. I've heard it repeated that someone like Justice Haynes just wasn't a good fit because he was a power back (1,473 yards, 6.5 YPC and 19 TDs in his career).
Then for instance you point out Pittman,, kind of the gold standard for offensive line coaches isn't a fit for the same basic reason. He'd want to maul opponents and DeBoer does finesse. I'm not saying it HAS To be Pittman, but this built in weakness (in both senses) in DeBoer's system really does need to be addressed because it's the Achilles heel.
I know some people less familiar with DeBoer tend to just be like yeah well it's the personnel here, that are the cause for the ineffective run game. It's just an ineffective run game, period, it's a systemic flaw. For instance, his much lauded 2023 Washington team ran for 1.7 against Michigan and was completely, physically dominated. It just took playing a physical team to expose the flaw.
So, to me he shouldn't be looking for a fit for his system, he should be looking for a fix... if he can bring in someone that can install a running game and some physicality into his offense, then it becomes as great as people thought it was.