Here's the video: https://www.youtube.com/watch?v=w6rkhvdAqHU - This Flash Drive has Literally Every File

The contents of the file are based on the path used to access it, correct. It uses MTP rather than emulating a normal flash drive though, which makes this kind of project much easier.

They also suggest that you can do other things using the same technique, like hiding a folder unless you know its exact name, only showing files if you navigate to certain other folders first, or because the esp32 stick being used contains a screen it could run a copy of doom controlled by navigating through folders.