To add to your post, states have ZERO say in regards to OEM vehicles. If the vehicle can be sold in the US, it is automatically legal in every state.
Emissions can make you car "not legal". If you buy a new vehicle in Texas, it will not "work" out of the box in Cali, without significant $ thrown at it "for" the environment.
California is special, the stickers on the window out there will say something to the effect, California emissions ready.