The really insane thing is that Trump faced charges for the 34 crimes he committed before taking office, but not the insurrection he incited on January 6, which should have been the easiest one to prosecute. We all saw it happen. It was basically the equivalent of watching somebody shoot someone else dead on live TV. There doesn't need to be a lengthy "investigation"; just drag his ass directly into court, give him a token chance to flail around trying to excuse himself, and then throw the book at him.
Ultimately, history will remember Biden the same way it remembers Neville Chamberlain, and good riddance. Assuming, of course, that we survive this mess long enough for there to be any history to remember any of it.