I throwing it out there, since digital subworld seems likely. I think there is at least 3 levels.
1. Original where Gridman was impaled.
2. Where everyone lives now, due to Gridman doing something last resort.
3. Sublayer for fighting.
And the kanji statues is just the state of the original world, before Gridman froze it.
Don't know about how real world impacted though. Would be better if there is some consequence after each battle, that is imprinted in on the real world. But nobody actually tried to map the statues and confirm about their movement, I assume.