They'd just blow themselves up trying to figure out how it worked anyway.
Quoting: ~Newton's Own~ They have one power generation nuclear reactor.
They don't have an enrichment facility.
They need someone to enrich their uranium to weapons grade or sell them plutonium.
That would be big news.
Plus they need to design a warhead and have done no testing.
NK showed just how much trial and error there is in warhead development.
Claiming they have a functioning warhead (unless they bought one) is complete bull.
But they have no infrastructure to build warheads.
Unlike Iran. Tehran has a research reactor and theoretically could generate plutonium.