Writer Thomas Schnauz tweeted recently that the poster was made by marketing people without approval from the writers. It’s not canon. In the show, there is no $5M reward (that we know of, yet).
Which I think is going to be a big plot point in the finale. What Saul can actually be charged with is not clear, and I think it’s kept intentionally vague.
Jesse’s confession tape is a wild card. The Nazis stole it and should have destroyed it after watching it and laughing at Jesse crying. But maybe the cops found it after Walt killed them all? Hank and Steve are dead so that’s the only real concrete evidence for most of Walt’s career, and certainly Saul’s role in it.
Money laundering is also a wild card. They confiscated his laundering businesses, which is something. But also cops can confiscate whatever they want for almost any reason and you have to prove it was legally obtained to get it back. So they can do that even if they have no real evidence against Saul at all. To me, it would be plausible if he’s in tons of trouble after accountants pored over his books and discovered gazillions in illegal laundering and he goes to jail for a long time. It would also be plausible if, perhaps by osmosis from banking law expert Kim Wexler years ago, he was a money laundering whiz and covered his tracks completely. The writers could go either way.
Kim’s confession is there, but she herself says there’s no physical evidence and nothing might come of it. And Saul wasn’t really guilty of anything there, it’s just very suspicious that a presumed dead Cartel boss showed up to murder an innocent third party in his living room.
Obviously, he’s committed a lot of crimes. But what evidence cops have, besides his mere association with Walt, is unclear. His abandoning his practice, his home, his businesses, and going on the lam is suspicious, but he can just say he was scared of cartel blowback.
Oh, and the writers also said before the season started to pay attention to the Zafiro Anejo bottle cork, as it would be crucial to understand the ending. But we haven’t seen it since the opening scene of episode one. And at this point, I can’t even imagine what role it might have. I had some guesses earlier in the season, but they’ve pretty much all been ruled out.