I was also thinking about this the other day. Essentially we should be able to take advantage of the brain's superb ability to comprehend/remember locations in our day to day programming experience. This would lower the cognitive load of translating the codebase into a mental model, since locations are easier to remember (memory palace) and reason about.

On a related note, the Unison language [1] and its data structure of the codebase lends itself perfectly for this kind of visualization (since you get the dependency graph between functions for free). Imagine being able to see the whole codebase as some kind of large, coarsely detailed factory/assembly line, linking all your higher-level functions together. Only when you "get" sufficiently close, you can make out the inner connections between the functions.

[1] https://www.unisonweb.org/ - a programming language where the definitions themselves are content-addressed