Broken GTK themes Home Manager

I am trying to set my GTK3 theme to adw-gtk3 (specifically the dark variant) and all my color scheme preferences to dark. Ideally this would be done in my Home Manager config, but at this point just getting it to work imperatively would be a win.

While trying to follow this guide: Declarative GNOME configuration with NixOS, I somehow broke the theming for many apps. Even Nautilus from Gnome 44 uses the old Adwaita style, as seen below:

My current configuration is GitHub - mars-monkey/nix

Upon further troubleshooting efforts, I discovered that this issue was caused by trying to set the GTK theme to Adwaita, which somehow affected libadwaita applications. With code from the tutorial I was following, simply switching out adw-gtk3-dark, I was able to get theming how I liked it.