Can someone explain what the advantage of Nix is over Homebrew? I hear some stories where brew broke something, but I've never had any issues with it.

For me it's that my dotfiles and packages are consistent across all my envs. 2 Linux machines, 2 Mac machines.

I'm not sure if Homebrew has this - but it takes me a few seconds to spin up a new Mac entirely with everything i want (minus build times lol). With home brew i was fiddling with "oh yea, this package/lib/plugin is missing" for weeks.

edit: Also, all repos i have are also consistent. Ie i build my repos with specific versions of npm, rust, etc - all per repo, all consistent across all machines, all managed by Nix. Think node-env or py-env (or whatever they're called), but Nix and cross-language instead of specific to node or python ecosystems.

Homebrew has this. Check out Brewfiles and homebrew-bundle. If you want a (excuse self-promotion) dedicated but simple tool to bootstrap new systems: check out https://github.com/MikeMcQuaid/strap