Thanks ! As for your question, no i didn't follow a specific guide. More like multiple ressources here and there. Here are some of them :

https://josiahalenbrown.substack.com/p/installing-nixos-with-hyprland

https://wiki.hyprland.org/Nix/

https://nixos.wiki/wiki/Flakes

https://nix-community.github.io/home-manager/

https://josiahalenbrown.substack.com/p/managing-your-nixos-configuration

If you need some inspiration, feel free to check my dotfiles