If they're vaccinating their own people, it's likely they're giving priority to the military (thanks to NK's "Military First Policy" and to their "Core Class."

NK divides their population into three strata; "Core" (regime loyalists), "Wavering" (average citizens) and "Hostile" (everyone the regime considers disloyal and undesirable).

During the 1990s North Korean Famine, NK prioritized aid delivery to its Core Class (and even allowed them to skim/steal some of it to sell on the black market for profit). The rest of the population got nothing and is where most of the casualties came from.

It would not surprise me if they would/did do the same in regard to Covid vaccines as well.