Why?
I needed an excuse to make something in Zig (this was my second project in it) and coincidentally needed a way to see my hard drive usage without waiting for Windows to calculate it.
I end up using it probably at least a few times a week so it's been useful.
Usage
Open the app, see how much disk space you have left. Click on the entries to open the disk in the file explorer.
Internal libs
I might pull the small internal library used here out into a library of its own but that would either be something I do because I need it elsewhere or because someone else makes a neat case for it.
If one were so inclined they could add the entire package as a dependency and
just point the package declaration at disk.zig (I think?) to use it as a lib.