Installing via Nix Darwin vs Nix Homebrew vs Nix Home Manager

So I just got started with Nix Darwin (using the Home Manager and Homebrew modules) and I am really liking it so far! Recently I posted some questions I had on the r/Nix subreddit, and I got a lot of great insights.

From this, I was able to distill the biggest blocker in my understanding of this ecosystem—installing packages. Some parts I understand: for example, Nix Home Manager installs packages on a per-user basis, while the other options install packages system wide. However, I still am unclear about the nuances/tradeoffs of the other options.

A lot of people have shared that they tend to use Homebrew for GUI applications—especially since some packages in the nix registry don't properly support MacOS. Beyond that, by default, it sets up applications in a way compatible with Spotlight (I guess you can do this with Nix Darwin too, but it requires injecting some custom bash code).

I'd say "standard" CLI packages (say, Node or Git) tend to be the source of my confusion. As of now, the biggest benefit from using Nix comes from its declarative nature. Am I missing any features by just using Homebrew to install things? I think there's some sort of isolation feature with Nix, but is it relevant in non-advanced workflows? Other than that, how does the way the packages are stored differ?

Thank you in advance for the advice and help! I appreciate your time :)