The guide follows an old stable build of NixOS but I want to do this on unstable channel. However after I done everything on that blog (also changing 22.11 to 23.05 whenever it shows up) I got to this error:
sudo nixos-rebuild switch
unpacking channels...
building Nix...
building the system configuration...
error: Invalid package attribute path 'qt6Packages qt6ct'
(use '--show-trace' to show detailed location information)
That did it, after you told me where the problem might be, I checked my mistakes and realized that I entered # nix-channel --add https://channels.nixos.org/nixos-unstable unstable rather than # nix-channel --add https://channels.nixos.org/nixos-unstable nixos after the channel update command that fixed itself, thank you!