I keep trying NixOS every years for few hours and then go back. When I first became aware of it, it was also available for FreeBSD kernel, but I guess was too busy with FreeBSD ports to look at it. I loved the idea, but it just seemed so hard compared to FreeBSD ports, that is.
Now few years later, with increase tolerance for complexity, and I finally decided to stop slacking, and switched one of my VMs to NixOS. Installation was not very straightforward, as I bootstrapped it from Ubuntu GNU/Linux, but it definitely wasn’t hard. Thanks to Nix Pills, I was even able to submit a package (or derivation) for Sagittarius Scheme.
Looking forward to continue use of it.