try again

modules/niri/default.nix

@@ -17,6 +17,15 @@ in {
       NIXOS_OZONE_WL = "1";
     };
 
+    environment.systemPackages = [
+      (pkgs.where-is-my-sddm-theme.override ({ themeConfig = (import ./sddm.theme.nix { config = config; }).style; }))
+    ];
+
+    services.displayManager.sddm = {
+      enable = true;
+      wayland.enable = true;
+      theme = "where_is_my_sddm_theme";
+    };
 
     programs.niri = {
       enable = true;

modules/niri/sddm.theme.nix

@@ -0,0 +1,47 @@
+{ config, ... }: let
+  base = config.theme.base;
+  surface = config.theme.surface;
+  text = config.theme.text;
+in {
+  style = ''
+    [General]
+    # Password mask character
+    passwordCharacter=*
+    # Mask password characters or not ("true" or "false")
+    passwordMask=true
+    # value "1" is all display width, "0.5" is a half of display width etc.
+    passwordInputWidth=0.5
+    # Background color of password input
+    passwordInputBackground=${surface}
+    # Radius of password input corners
+    passwordInputRadius=8
+    # "true" for visible cursor, "false"
+    passwordInputCursorVisible=false
+    # Font size of password (in points)
+    passwordFontSize=96
+    passwordCursorColor=random
+    passwordTextColor=
+
+    # Show or not sessions choose label
+    showSessionsByDefault=false
+    # Font size of sessions choose label (in points).
+    sessionsFontSize=24
+
+    # Show or not users choose label
+    showUsersByDefault=false
+    # Font size of users choose label (in points)
+    usersFontSize=48
+
+    # Path to background image
+    background=
+    # Or use just one color
+    backgroundFill=${base}
+    backgroundFillMode=aspect
+
+    # Default text color for all labels
+    basicTextColor=${text}
+
+    # Radius of background blur
+    blurRadius=
+  '';
+}