[takeda]

I don't think what you said necessarily contradicts what I said.

NixOS is easy to use as long as as what you're trying to do is contained within the configuration, then set up is pretty much just editing that configuration file (which essentially is just series of dictionaries and lists). I wouldn't for example have with installing NixOS for my grandparents.

Here's example config when that's true: https://github.com/areina/nixos-config/blob/master/thinkpad-...

If you want to do something that's not covered then you'll have to learn Nix, and that part is indeed hard, because it's like configuring linux through use of saltstack/chef/puppet/ansible through a functional language (which many people don't have experience with), but as you said it pays off.

I think the hardest part is the paradigm shift where everything you do is no longer imperative but declarative. It also doesn't help that documentation is always behind what nixpkgs can do and Nix functionality would cover multiple books.