Is it just me, or does NixOS almost feel like a different operating system from Linux?

I don't think NixOS is used by many companies, so it's not really a skill that will likely lead to employment. Most companies use containers and tools like ansible which is accomplishing something similar to nix.

Well Linux isn't an operating system, it's a kernel. The difference is really just the design philosophy of the package manager. As someone very experienced with NixOs, people are starting to catch up with it, but it's much more advanced than the docker kubernetes mess most developers end up working with.

Linux is a kernel. At the beginning, software, especially userland software mimicked Unix conventions. There is very little requiring that anything work the way it does, except for inertia and convention. As cloud native conventions gain steam, a lot of them are working their way backwards into things like Nix. Having spent some time working with things like K8s and Packet and cloud-init quite a bit, I welcome declarative instantiating and configuration at the OS level, at least for those use cases. Stuff like Ansible, Chef, Puppet, Salt etc have been the middleware between the legacy OS layer stuff and a declarative CM system, but they all have an absolute pile of complex scripts and tests to make sure that when you say “I want this package installed”, it knows how to do it correctly and safely on the target system. Using a leaner declarative model at the package level makes it a lot simpler to declare the desired state.

I am pretty bearish that it will ever see overwhelming adoption for desktop users, but I see it having a ton of relevance when you want to orchestrate a whole butt load of server instances

I don't know if you've used Emacs, but NixOS ALMOST feels to Linux how Doom Emacs is to GNU/Emacs. Not including all the benefits like reproducability, it feels like a reliable framework placed on top of Linux in the same was Doom Emacs is a framework on top of Emacs.

I don't believe NixOS prevents you from using the standard terminal commands or editing config files. It hooks you up with a different set of tools, ones which are better in some respects, but it doesn't force you to use them.

nix-env -iA is there for a reason, they recognize that sometimes perfection is the enemy of good #^-#

Having been in a similar situation to you, I say go for it. Arch taught me the basics about Linux that I think everyone should know to understand what Nix does under the hood, but as soon as I saw how well NixOS worked on my secondary machine I switched my primary over and I'm not regretting it in the slightest.

That's not to say Arch is a bad distro, in fact I'd say 99% of my Linux knowledge comes from that excellent community, it really is KISS, but it makes no secret out of what this actually means: making it simple for the maintainer by delivering an almost untouched upstream, which I agree brings the ecosystem forward as it pushes toward a bazaar model where everything works together without the distributor doing too much work of their own. But if you want to keep a system clean in the long run, at one point you realize that you need a system like Ansible (which for me retrospectively has shortcomings that can only be fixed in the underlying system) or Nix integrated in your base system, which NixOS does.

Linux is Linux, nix is just a tool to essentially build a view of the root filesystem in a special way. In the end, it's not that different than if you do everything from Ansible playbooks, in a Dockerfile, from Puppet/Chef or any other automation technologies.

Heck, if you look closely at Debian/Ubuntu, there's the whole debconf system that lets you configure packages directly from the package manager, and it generates configuration files based of that. If you install Postfix on Debian, it's going to ask you how you want to use it and it generates some ready to use configuration files. Then if you install Dovecot, it might just work out of the box using that configuration to know how you set up Postfix and let you fetch your emails over IMAP. It's not nearly as comprehensive as nix does it, but the concept of a main configuration file is far from new, nix just pushed it to a whole other level.

Building packages also differ wildly between distros. ArchLinux uses simple PKGBUILD files that are essentially just bash scripts. Debian uses debhelper and dh_make, and lets you do some really crazy things with the build system to reduce boilerplate so that all Python packages for example are built exactly the same way and often in just a few lines.

Distros also put files in different places. On Debian, system-wide systemd units are in /lib/systemd, but it's /usr/lib/systemd on Arch. Distros use different tools: apt, yum, dnf, pacman, pkg, etc. Debian in particular really likes to ship with heavily customized configurations. For example, if you install NGINX on Debian or Ubuntu, you have a /etc/nginx/sites-{available,enabled} and it's got a helper script to easily enable/disable a site. On Arch, there's no folders, you get a plain basic default /etc/nginx/nginx.conf. On macOS, I have that config in /usr/local/etc/nginx/nginx.conf. The default location of configuration files is inherently a compile-time property, just so happens that most distros puts it in the same place.

I've worked with part-time admins / web developers that completely panic when they SSH into a system that's not Ubuntu and they don't know how to do anything.

If you like NixOS, just enjoy and you'll be fine. Completely different means of achieving the same things, and if anything will make you more aware of potential variations. Nothing preventing you from having VMs with more classical distros to keep up to date with how to admin those. A lot of things still work the same: you can still systemctl restart a service, you've still got a bash shell that works exactly the same. You're just going to manipulate and template nix files instead of directly modifying configuration files, but still ends up generating that file for the software to use.

I use Arch for all my stuff, and Ubuntu at work. Because I use one doesn't make me not well versed in the others. NixOS have real advantages, and I know some companies that have fleets of NixOS servers.

I've been using replit to host some small projects, it's a real pain as replit is so heavily relied on nix packages.

From what I've heard from NixOS users, your intuition seems right. When you learn NixOS, you learn NixOS rather than Linux. The question is, what your goals are. If you want to get a job as a Linux sysadmin, you'd probably be better off using a more common distro. But if you just want to use Linux privately, dive into whatever seems most exciting to you or fulfills your needs the best.

IMO if you get more into it it’s still really linuxy. You still use the same software under the hood, especially when writing custom modules. A ton of knowledge transfers, with more new cool stuff to learn.

A ton of stuff you can just configure manually. Not everything has to be done in nix, but most people prefer to do it - I do it for example to have the same system between my laptop and PC. Really useful.

I was interested in NixOS until I saw no reference of a specific software I want. Literally not a single search result.

So, I guess its biggest flaw for me is that it cannot beat Arch Linux's catalogue. So, maybe in a year I'll check again.