The way to interact with the OS is significantly different from almost all other Linux distros. There is no shell, no DE. This feels like a lot more than "a custom paint job".
Is Ubuntu an OS? Mint?
Neither have built the package managment system, or the kernel, the DE(s), the utilities (maybe some but certainly not all).
What about CentOS? Or Bazzite? Or even Android?
Is macOS an OS, or "a custom BSD distro"?
And if none of those are OSs, does a Linux-based OS even exist? If not, what's the point of the distinction?
> Linus Torvalds and DHH are the only two arrogant people in tech
Are you feeling ok bud?
This is what Wikipedia says about NixOS:
> NixOS is a Linux distribution built around the Nix package manager.
This is about CentOS:
> CentOS (from Community Enterprise Operating System; also known as CentOS Linux) is a discontinued Linux distribution that provided a free and open-source community-supported computing platform, functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL).