I also wonder what is the Russian exchange for NK soldiers in Ukraine.
The FT writes, with reference to South Korean and Western sources, that the North Koreans want:
1) Invaluable battlefield experience against Western trained and equipped forces. Something they can't get anywhere else in the world.
2) Fuel. Security Council sanctions had previously limited fuel supplies to the DPRK to starvation levels.
3) Food. A stable problem since the 90s.
4) Help on their ballistic missile program, and also developing their reconnaissance capabilities - including satellites.
Russia gives NK legitimacy - that's the main exchange. From being a cooperative partner for the West in curbing NK nuclear ambitions, and helping to isolate the country, Russia has instead swung to being a full fledged ally. I think that's the main win for Kim.
For us, in turn, he has been incredibly useful. Western press report that HALF of the artillery shells used at the front this year by Russia were supplied by NK. HALF! That's approximately 3 million shells.
Meanwhile, the Czech prime minister has managed to crowdfund the purchase of only 500,000 shells for Ukraine - after searching the entire world.
Also, the guys were getting now seem to be very highly trained. Their discipline and morale are expected to be superior to that of our line formations. A few small details about them in the screenshot below:

IMG_3935.jpeg