It really would be stupid of the DMV to have both Os and 0s in license plates. If, say, JACKO and JACK0 were distinct plates, policing would be impossible. Some folks might like that. But it defeats the point of license plates in the first place.
The only vanity plate I was ever really happy with was my ham radio call sign. I quit using that (though I could have continued) when I stopped being active as a ham. Here in HI I get a special EV license plate which I like better than a vanity plate.
My mother had a plate with the name of her favorite 19th-century author, and so people thought that was her name.