I had my time trying every new distro that would be popping up on Linux related magazines CD/DVDs up to the mid-2000's (they still do in some European countries), unless it comes on a laptop I can get at the mall computer store, or some customer imposes it on our delivery contract, not really something I want to give a chance to.
Me, too! That was a blessed part of my childhood and adolescence.
You're not entirely wrong about the comparison to Gentoo, but I do think NixOS is more practical than Gentoo.
It's happening: Companies are adopting Nix [0] and you may see such requirement come up some time.
I am yet to see any classical VM deployment isn't one variation of Debian, Ubuntu, Red-Hat, SuSE.
Note how that list has a certain startup feeling to the company list, not boring big corp.
So Nix would let us avoid the Ansible playbook by just installing the Nix file but Ansible playbook is extremely rock solid so it feels like a problem we don't have. Also, we do pay for support for Cassandra to someone and while they officially would support us running on Nix, it's clear their support technicians are much more comfortable with RH or Debian based systems.
Several of those companies (replit) are building their business on nix.
With nix, even containers are optional.
My point was that some businesses are tying their destiny to nix - in my experience this is a sign that an open-source project will gain corporate benefactors keeping it afloat + making it safer for others to adopt.
Nix does not require NixOS, and I would even wager that in corporate dev environments it's most often used in a standalone manner.
You can install Nix on Debian/Ubuntu/RedHat, get a reproducible local dev environment and build reproducible OCI images that can be deployed to K8S/Cloud Run/Fargate/etc [0], without ever touching NixOS.
[0]: https://nix.dev/tutorials/nixos/building-and-running-docker-...