I'm going back to my previous employer, where they have a written track record of what I did at the company. But even then, many teams at the company do not want me, and feel like I am both overqualified for the technical roles, but also underqualified/a bad cultural fit to lead a big engineering team
Sorry to hear that. Sounds like you and I are kind of in the same boat.
Unfortunately my previous employer that wasn't a startup no longer exists (it was 14 years ago after all, they got crushed by the 1..2 punch of the dot com crash and the 2008 recession).