If NK was smart in making the deal with Russia, they likely got technology transfer and/or embargoed supplies of things they aren’t good at making like electro-optics, guidance systems, raw titanium, oil, missile software, avionics, etc instead of just money. Money they can counterfeit or blackmail the west for, the rest are verboten via sanctions.
THATS what has South Korea’s jimmies rustled - the big list of potential trade items NK could get, that’d help NK be much more effective if the DMZ gets ‘kinetic’ again. At the very least NK gets battlefield feedback on the supplied hardware.