It’s not really self-reliance, but more about centering humanity. Essentially, the laws of the world are universal and materially driven, but that once aware of this fact and humanity’s role in this process, we can harness that and direct it towards our own ends. The prolewiki page on Juche is extensive.

Juche is just Socialism with Korean Characteristics.

it unfairly gets translated to self reliance, but its main point is that the dprk faces specific conditions that are unique and that simply following a soviet/sino/etc model towards socialism will not be a comprehensive fit. therefore, koreans, as the movers of their destiny, should carve a unique path towards socialism, relying on the three theaters of revolutions: revolution in the ideological sphere, revolution in the technical sphere , and revolution in the cultural sphere.