I mostly want to make one thing clear: Russia builds most of their weapons itself. That's kind of the point of being a super-power, even one which has been in decline for some time.
The notion that North Korea could make much of an impact on Russia's capability by weapons deliveries is absurd. Iran is much more capable, but still far below Russia's own production capabilities.
Russia does import dual use goods and general industrial goods to support its weapon production, and they used to buy those goods wherever they wanted: The USA, the EU, China, famously neutral-as-long-as-it's-good-for-business Switzerland, etc. The goods so imported might directly go into a weapons system - for example drones shot down in Ukraine were found to contain lots of off-the-shelf western components.
I don't think anyone knows right now when and if Russia will be able to easily buy western high tech components again (could be a single year, could be after a regime change in 20 years...), but China and some quickly industrializing other countries are happy to pick up the slack as good as they can.