Nix isn't so exotic anymore. Every company for which I interviewed about a year ago used Nix

And every person I met today had a parrot on their shoulder. Doesn't really mean it applies to the general public (here meaning most developers out there).

I'd say <1% of all developers world wide have even heard of Nix.

It is used in production much, much more widely than Haskell is, though it remains far from the most common way to do builds or deployments.