I'm running macOS Mojave now, and hopefully this will fix some bugs so that I'll be able to use Nix as my package manager
What bugs are you running into? I have been using Nix on my MacBook with home-manager a couple of months now with relatively little effort. Every now and then I run into a package that does not build, but usually it's easy to fix and submit upstream.
There is also nix-darwin for managing macOS NixOS-style: https://github.com/LnL7/nix-darwin
Of course, nothing beats the real experience, so I am running NixOS on my workstation.