Just like any other package manager, this information can be queried without grep.

  nix-store --query --references /run/current-system
  # or with new CLI:
  nix path-info --recursive /run/current-system

This information is managed and tracked for you. And while I understand the desire to have "normal" FHS paths, the hashing and the injection of the hashes (think "tags") is exactly the mechanism that makes dependency tracking possible to do automatically. This is similar to the trick by log aggregation tools that assign each source event a UUID to make it possible to search and find it in all sorts of unexpected places. Otherwise how would you know what "/usr/bin/bash" really means if you came across it in an error log? What version was it at THAT EXACT MOMENT? That hash in the path is the tag that enables all of it to work.