North Korea is especially difficult for a Burgerlander like me to get a clear picture of. I hope the Kim dynasty largely acts as a state figurehead, but I haven’t investigated and have no idea.
China does have a limited capitalism going on right now, which, if I understand correctly, is a part of the ongoing Reform and Opening Up project. From my (still fairly ignorant) P.O.V., I can’t help but imagine a risk to this strategy, where the capitalists become strong enough to wrest control. The project has brought hundreds of millions out of poverty, though. The government recently took the capitalist real estate speculators to heel (to the dismay of capitalists everywhere and the delight of people just wanting a place to live), so it seems they haven’t lost control. Their professed long-term plan is to phase out capitalism entirely.
It’s worth noting that no Marxist worth their salt will paint any of these socialist countries as utopias, especially given that Marxists reject utopian socialisms.