They are lacking in most everything and have almost no money. Any initial materials will be humanitarian aid in the form of food, medicine, and clothing. Anyone with the ability will leave for South Korea and send money home for basic necessities.
That’s realistic.
Huge money will flow in and be distributed by Kim. Of course their ‘elite’ will recieve most of it, for nothing, and they’ll be the support of any early consumer spending.
Would be wise of Kim to give huge bonuses to Army personell to start businesses. That’s the only social group that could develop a business infrastructure.
But I expect an elies/criminals business development as happened in other communist countries.
What might work is opening sweatshops in NK. Lots of sweatshops. Have them make clothing, assemble electronics, whatever. Have stores next to the sweatshops where they can buy food.
It will take GENERATIONS to undo what the Kims have done to the people there.