What kind of issues are you having?
Also, my Mac is 256gb which feels far too cramped for Nix. I'd really only recommend it if you're working with 512gb or more.
home-manager works better than I'd expect. At least I don't have to spend time configuring vim, git and shell prompt.
But overall, Nix on MacOS feels like a hack, behaves like a hack... because it's essentially a hack...
I'm waiting for the first reports of Lenovo's t14s gen 6 with Snapdragon X Elite.
If that's really all you use it for, and you already use Home Manager, the Homebrew module for Nix-Darwin works fine in Home Manager with some small tweaks. I use that with a custom, per-user Homebrew prefix to keep Homebrew out of the way except for the task of installing casks.