I'm sure there are flakes that can do that, but I just use the config file, adding things as I find I need them. Flakes weren't really all that well documented when I first installed it so I never messed around with them. Out of box though, it was fairly decent for relatively simple needs. If I remember correctly, the graphical install could set you up with any of a half dozen different DEs out of the box.

One heads up. While NixOS is a Linux distribution, it is radically different design philosophy from every other Linux distribution I've ever used. In some ways better and far easier to setup and maintain, and sometimes, as headache inducing as Gentoo or Arch. Once you have it setup to your liking, though, it has proven incredibly solid and hard to break.

Here's a redacted copy of my configuration.nix file. I really need to clean it up, reorganize, and remove things I'm not using anymore, but it's what I'm running on my desktop. Basically hasn't changed since KDE6 came out something like a year ago. I think the last change I made after that was when I finally added flatpak support.

https://pastebin.com/8G7Hv4y2

There are thousands of packages. Download off the internet and boot it. Just like a normal distro mostly. Nix is the single largest package manager even far surpassing arch and others. If they could refine the process it could be the end all be all right new to Debian and mint.

I've used nix for roughly a year. Flakes is the way to go. It's the most simple cut and dry shit works distro aside from Linux mint but the caveat is you have to essentially learn how the nix config file works. You can install your configuration file on any machine, anytime, anywhere and it'll boot as your exact carbon copy. Its a great distro you can trust to maintain with two files entirely. Cake to remember and backup.

Downsides are keeping config file backed up often. And knowing that anything you want done has to go into config document. I can answer any questions. I'm busy so I can't type more.