I don't think a beginner should use Home Manager, because that's an extra layer on the already not-beginner-friendly Nix ecosystem.
Home Manager isn't necessary for declarative management of the user environment -- Nix flakes can do this, too. A long time ago, I kept a single `flake.nix` in my home directory describing the packages that each of my machines needed, and ran `nix profile install .#packages.<machine>` to install them into my user profile. By doing things this way, I learned a lot about writing flakes, and this transferred to other places I used Nix.
What this doesn't do that Home Manager does is dotfile management, but that's actually why I avoided HM originally. First, HM's approach is a bit clunky for my taste: each change to the configuration must be followed by running `home-manager switch` for the changes to take effect. I found this to slow down the edit-and-test loop when making changes to my shell config, etc. Second, the idea of doing all configuration in the same Nix language is cool, but most of the documentation found online about configuring, etc., `git`, will refer to the tool's usual method of configuration.
So instead, I made a quick Python script that manages package installation with Nix, and dotfile management with GNU Stow. The dotfiles and Nix configuration all go into the same git repository in my home directory, so they are tracked together. I've been using this approach to manage several machines for a few years now, and it's been more than sufficient for my needs.
That way you don’t have to do home-manager switch when a dot file changes.
So that's just to say I think it at least warrants a mention, it's helpful for a beginner to be aware of, even if they don't use it (once informed they can decide for themselves if they need that piece or not).
Nix doesn't need any more home-manager tutorials, because it doesn't need any more small-time tinkerers. It would benefit more from becoming essential to a bunch of businesses who will become invested in making their own developer experience acceptable at scale, and who will have to improve Nix to that end.
Pretty soon a bunch of people are going to realise they actually do need the exact same version of every tool in every toolchain on every machine in a team, to make use of the transformative caching abilities of tools like Bazel and Buck2. And if that catches on, I would not be surprised to see an alternative Nix frontend configured in Starlark, like every other tool in that arena. There's already a buck2-nix that generates dhall under the hood.
As far as I'm aware multi-user (as in human login users) Linux systems are almost entirely - literally - academic. Supporting it does leave some warts and complexity to be experienced by the majority single-user system users.
Yes, home-manager + darwin is added complexity that is making this harder for me; when I am encountering problems I am not always clear on where in the three systems it lies. But I probably wouldn't be journeying into Nix if it wasn't for home-manager + darwin; what I want is managing my workstation and setting up ad-hoc development environments, not configure servers.
My dotfiles managed by nix(-darwin) and home-manager breaks every time I update my pins, and I find myself having to bisect which commit introduced the issues. Given that, I just don't see how that would scale to a full OS, let alone to a team at work. 1000% better simpler with understandable Dockerfile and Kubernetes YAML manifests, or with Ansible YAML. At least every folk can StackOverflow and ChatGPT it to a working state, and have it work for a considerable amount of time without further maintenance.
In the very worst case, you update components individually until you find the offending one.
I've used both NixOS and nix-darwin for 2 years professionally now as daily drivers, and have had generally nothing but great success. I'm not fearing an OS update actively breaking my environment (which I can't say the same for macOS, as much as I am a fanboy of Apple).
Some examples: managing patches for applications is doable with NixOS. With overlays they survive updates and if they no longer apply, build fail before they can have production impact. Doing the same with docker is a nightmare and different for every dockerfile without a common interface around it. Ansible takes the previous state of the system into account which is terrible if you want to manage it fully declarative. Worst case in NixOS you do a reboot and your config applies almost no matter the previous state.
And that you can leave something running without maintenance is naive and it will start to slowly rot.
But with all due respect, asserting that everything outside of home manager is “not worth using” is fertilizer.
The fact that smart companies (TailScale and Shopify come to mind, but there are zillions) are willing to cope with those (obnoxious) gaps is very, very strong evidence that there’s a lot worth using.
git was considered too hard, inadequately documented, maliciously baroque for years before GitHub happened.
Nix solves a harder (and more important) problem in a similar way.