North Korea is fascist. Fascism is not distinctly left-wing. And Singapore is already starting to notice that it's set itself up for failure in many areas.
North Korea is Socialism taken to its extreme. No different than Soviet Russia, Cambodia, or 20th century china. When the state takes absolute control over the means of production, the result is always the same. It's not a question of nationalism (Hong Kong is extremely nationalist and exclusionary) or authoritarianism (as singapore is one the most authoritarian countries in the world). It's question of economics.
North Korea and Singapore are similar in many ways. They both run by one party and one family. The social freedoms of both countries are highly restricted. Both states execute citizens and implement excessive capital punishments. However, one chose Capitalism and the other chose socialism, and 40 years later we see the results.