I make California independence jokes a lot as a meme in my community and with my family but if I was being entirely serious, I think it's an entirely impossible endeavor, especially at the moment.
The primary concern is water before anything else, and I'd say hat unless a Calexit platform aggressively and thoughtfully proposed a solution for the water issue, the concept is dead on arrival.
I'd also argue that it's still settler colonial in nature, and without a commited anti-colonial and anti-imperialist line/faction within the movement it won't really differ much from how the US operates.
Perhaps if the water issue was addressed along with strong west coast unity it would lead somewhere but I regard the concept as pretty silly at the moment.