What do you got?

It is not at all acceptable. This one is OK, but informal:

What have you got in there?

It's dialectal and unacceptable in AmE.

Whatcha got?

This would be said as: "Wady-yah got in there?" or "Wad-dja got in there?" or "Watch-you got in there?" (never as: "What do you got in there?"), meaning: "What do you have in there?" or "What have you got in there?" This is how many people speak in casual speech.

But what city is the setting of the novel?
The stlye/speech combinations in this translation are conflicting.
A crude bully policeman might ask:

Whatcha got in dere? (My misspelling is deliberate, because he would have an accent and not speak the words like this, not like an English school teacher.)

Ya got summit' in dere? (DO you have something in there?)

Like e.g. on hearing that phrase, would you get an inkling of where exactly the speaker is from or about his schooling?

No, because vernacular has conflicting elements of an educated and an uneducated person. A crude bully policeman might ask:

Whatcha got in dere? (Misspelling is deliberate, to capture the accent.)