The Norks are heavily in bed with both Pakistan & Iran. They could have easily bought what pieces (If not the whole assembly!) they needed from either or both places.
Could have but there is nothing to indicate that they did.
We’d have heard more than just theories it was going on.
If they were, I’m sure our intelligence would know, and Pakistan would be on the chopping block as well as Iran. But mostly it’s just China and North Korea. If anyone helped them it’s China for sure. China has the most to gain from a war between the US and North Korea. If North Korea detonated one bomb in say.....New York City, it would wreck the US financially, China would be way ahead, and they would have plausible deniability in any involvement.
My personal opinion is that there is something going on we aren’t being told, I think there is a growing list of countries with major grievances against the US and that the plan is to take the US off the world stage through one surprise strike. North Korea has a part to play in that plan. Pretty sure we’re going to wake up one day with no power, no communications, and nobody is going to know what happened.