Yea I don't see Nix doing much here particularly, but for me I typically would do something like this to make the system as consistent as possible over a long period of time without being actively maintained.

I guess this does ensure the key `journal` command works exactly the same because the dateutils binary will stay locked to the version in the `flake.lock`.

I would have assumed that nvim would also be locked because that's where I would expect more possible breaking changes with the existing special config.

With little tools/projects like these I could easily see months-years before it would get any active attention from me again (or simply I wouldn't be using it; so it doesn't matter).