I think there are a broad range of candidates that Trump can beat. Kamala Harris and Amy Klobuchar, for example, is not beating Trump.I think Biden is the only one Trump can beat. While Newsome or Whitmer would be distasteful to decent Americans, they would come off as alert adults and probably attract a lot of undecideds.
I think there are a handful of combinations that could beat Trump. Gavin and Whitmer is one of them.