Michigan is a mostly blue state that only once has voted GOP in a presidential race in the last 34 years (I think we all know which one), and that was an anomaly (Trump got fewer votes that year than Romney did in 2012). So all of the statewide offices remaining Dem was no surprise (especially considering , uh, "candidate quality" in the wise words of Mitch McConnell...e.g., the guy the GOP put up for AG is under investigation for election tampering from 2020...can't make this shit up). Whitmer won big for the same reason DeSantis did in FL, which is that things are good and getting better for almost everyone. She spends all her political capital on infrastructure improvements, and while people don't like sitting in traffic, they do like broken shit getting noticeably fixed.

The real surprise here was that both houses of the legislature went democrat. That is a direct result of a citizen-led effort in 2020 to get a constitutional amendment that guarantees non-partisan redistricting for both Congress and the state houses. It worked, and surprise, surprise, for once the party with more votes got a majority. All in all it was really a best case scenario given the natural headwinds the incumbent president's party face.