You are right that this is state dependent, and I am certainly not a lawyer. I have no direct knowledge about WI. My personal experience concerns NJ/NY.

Still, what I understood at the time is that, if the employer is not paying you at all during non-compete period, they will have a hard time enforcing it anywhere.

I am also surprised by the claim that it could cost millions to litigate about something like this, how confident are you of that number?

(And about CA, my understanding was that noncompetes are simply to allowed there, so it wouldn't even apply)