After playing around with home-manager for a bit, I realized what I really wanted was to have nix-darwin manage my system and use my home-manager config as a module. It took a bit of trial and error and searching to figure out how to make this work, but I did eventually find a way. With nix-darwin, I set up my nix and macOS settings. With home-manager, I installed my system packages (configured those) and shell aliases. I still need to do some work to set up git, my shell PS1, and to see if I can configure iTerm from here, but it’s the most promising progress I’ve had so far.