I think that no one is born with technology already in their pocket, it's like Christopher Columbus' egg, you always need someone who first achieves a certain goal or creates an invention, then it's easier for others to try to understand how he did it and make it same or similar, and if you have help it's always easier.
In any case, in the armaments sector, the nation needs people who have a good technical, engineering and scientific basis, to then put into practice what they have learned on a theoretical level.
Looking at the type of new armaments created by the DPRK, one might think that the North Koreans have carefully observed and studied both Eastern and Western weapons systems, adapting them to their needs and production capabilities.
So I think so! the Chinese may also have helped, but the same must be said for the help coming from Russia or the so-called Western countries.
But the current results are probably the goal reached after decades of studies and planning which certainly saw an important acceleration under the command of Kim Jong-un.