@cwebber yes, but. I was using nixos in 2015-16 or so, at which time docker was still young enough (iirc) that it required unionfs and other weird hacks. We could have gone Full Declarative back then, but the Dockerfile - it's just shell commands one after the other - is a much easier sell to sysadmins than "btw you have to learn scheme" or even "btw you have to learn this weird ml-syntax-but-no-types lazy-evaluated language you've never seen before"

I don't know the state of the art on Guix, but even in 2023 I would still be cautious about recommending Nix for packaging, say, a large Rails + React monolith - especially a closed-source/internal one