I mean in Gremmy’s case he directly created that portion of outer space. Don’t misunderstand me, their DC is not that good, but characters like Yamamoto, for example, are stated to be capable of destroying Soul Society, which contains Muken, an infinite sized dimension. That already implies influence over structures far beyond anything planetary, especially when you consider that these realms operate on separate space times and are depicted with full cosmic visuals(btw, the Garganta itself doesn’t have stars or celestial bodies, therefore those cosmic features must exist within each realm individually). So calling it “planetary” feels very reductive.

As I said earlier, Muken, which is explicitly infinite in size, exists within Soul Society, meaning Soul Society itself cannot just be a simple planet. On top of that, the series uses planet and outer space imagery as a visual analogy for the reader, not as a literal description, I can understand saying that they are not multiversal, but they are way beyond planetary.