It's not so much Diddy getting off as he indirectly benefits from Trump firing the current prosecutors and US Southern District DA who are charging Diddy since those are the same people who charged Trump. Trump's replacements would have less interest in prosecuting Diddy and more likely to offer him a more generous plea deal to wrap it up quickly.
Southern District has never charged Trump with anything. That was the Manhattan DA's office under Alvin Bragg. SDNY in 2018, actually declined to charge Trump in the same case, the Cohen mess, the Stormy Daniels shyt, and they just weren't interested for whatever reason, political or not. So it was passed to Vance's office, who declined to charge, and finally to Bragg who resurrected it.
Damian Williams has never charged Trump either, and he almost 100% out at Southern District, as is every US Attorney in the country. If he is out, and Trump selects someone like.....RFK Jr. to run things, then a lot of the other prosecutors will step down too.
As for the Puff case, they are working on back channels already is my guess to get a pardon post conviction. There wouldn't a generous plea bargain because of the severity of the charges and the public knowledge.