I'm as local as they come

A: We try to hire local people.
B: Hey, I’m as local as they come. South Side, born and bred.

Question: I’m as local as they come.
What does “as they come” mean here?

I’m as local as any local person. | I’m as local as anyone could be. | I’m as local as possible.

Maybe this is easier to understand: I am looking for a fast car. I want it to be as fast as they come! (Out of all of your cars, I want the car that is faster than the other cars that come here.)

it’s kind of a slang way to say: I’m from here. I’m as native to this area as can be. This is my hometown.

As can be.
I’m local.
I AM local.
I’m as local as anyone else you will see.

If you learn English from Shameless you may have some interesting conversations if you use some of their more colorful vocabulary.