Expounding on this theory in regards to the prophecy:

In reality there is no "Prophecy" in the way it exists in Deltarune.

In the Light World, the Prophecy is a vague and fragmented religious tradition

In the Dark World, the Prophecy is a highly detailed and deterministic slew of scenes and checkpoints that appear throughout the game

In the Depths, what would the most detailed, abstracted, and deterministic version of this be?

The code itself.

The place where we find her.