There's two wildly different stories at play in "Okja". The first story, the American one, deals with the cartoonish world of corporate agribusiness. The plot in that story is minimal- it's mainly just an excuse for loud imagery and louder performances. The second plot, the Korean one, is quite a bit more down to earth. It's the story of Mi-ja (played by Ahn Seo-hyun) and her pet super-pig Okja.
Their friendship is heartwarming. Our only context for it is an extended romp in the woods between the two best friends, but this is more than enough. Mi-ja's only friend in the whole wide world is Okja. They are best buds and will do anything for each other. So when Mi-ja runs into the elaborate carnival that is the corporate plotline, well, it's little surprise that she just plain doesn't care.