Get Aizome.

Open Yukimi › Desktops, choose Aizome and make it the default, and Apply. Yukimi asks for your password, builds the new system once and offers a restart when the change needs one. The same choices, in a Sekka system's configuration:

calamares.desktops = [ "aizome" /* and any others */ ];
calamares.defaultDesktop = "aizome";

Aizome's own login screen is a choice there too, or from a terminal: sekka-update --choose calamares.loginScreen=aizome.

Add Sekka's flake and its Aizome module to your system's flake:

{
  inputs.sekka.url = "github:bitemyapp/sekka";
  outputs = { nixpkgs, sekka, ... }: {
    nixosConfigurations.example = nixpkgs.lib.nixosSystem {
      modules = [
        sekka.nixosModules.aizome
        { programs.aizome.enable = true; }
      ];
    };
  };
}

programs.aizome.enable brings everything Aizome stands on: the session, portals, NetworkManager, BlueZ, PipeWire, UPower, power profiles, UDisks2, AccountsService, CUPS, GeoClue, GNOME Keyring, polkit, the fonts, and fish for the terminal. Add programs.aizome.greeter.enable = true; for Aizome's own login screen, or keep the one you have: Aizome adds itself to its sessions.

Add Sekka's binary cache too, and Aizome's packages download rather than compile:

nix.settings = {
  extra-substituters = [ "https://cache.sekka.computer" ];
  extra-trusted-public-keys = [
    "cache.sekka.computer-1:JJsOkmRt3iCwjvJrol8x2a7euU+kMV7iHaDSFzofA+Y="
  ];
};