How does something like this get implemented? A company has limited control over the gender composition of the board. The aggregate actions of myriad outside and independent shareholders may not align to produce the necessary result in aggregate. Furthermore, virtually all of these companies are foreign corporations, California has limited ability to modify the intrinsic nature of the board construction process -- it has no jurisdiction. The only obvious escape hatch that make this reliably executable in any sane legal framework is to guarantee that the CEO is female. Or to have a male member of the board exercise the "identify as female" clause if the shareholders in aggregate don't produce a board composition that meets this law. The whole thing is a setup for some absurd theatrics in the board room. I fail to see how this will produce a positive result for anyone.
That said, I am skeptical that this passes Constitutional muster. California has no jurisdiction over corporate law in the rest of the US, and (for good reason) nobody incorporates in California such that they would have jurisdiction. This is a publicity stunt that will stir up outrage by various factions and accomplish nothing.