This isn’t going to do anything. First of all, North Korea is probably not going to send battle ready soldiers to a foreign country. There’s really no reason for it. They might send ditch diggers for trenches.
Second of all, this isn’t going to move the needle on the battlefield. Russia already has more troops than Ukraine. They need more and better arms and ammunition, plus better support, training, airplanes, missiles, drones, commanders, etc. Basically Russia needs a completely different military.