Now I promise this isn't just a NixOS advocacy site; I do have some other content planned, honest! I just wanted to give a couple of examples of the using Nix as part of your daily workflow of building stuff.
Back in 2006, for reasons that made sense to me at the time, and make no sense to anyone at all now, I decided to buy some fonts and use them when writing my final-year thesis for university. I was writing my thesis in LaTeX. What followed was a week in which I read some pretty thorough documentation and slowly figured out how to convert fonts in normal TrueType and OpenType formats into the variety of formats that LaTeX needs, and how to install them.
I started using Linux as my main desktop OS in about the year 2000. I bought the Debian 2.1 "slink" CD-ROM set. At the time I also dabbled with other OSes too: Windows, BeOS, and also Minix. Over the last 20 years, through University and my career so far as a software engineer, Debian has been incredibly reliable, and has been my go-to choice whenever setting up a new machine. About five years ago I came across NixOS.