Use nix 2.23.3 (+add-nix-state-home), like nix-installer.

flake.nix

@@ -4,8 +4,6 @@
   description = "The Nixsa standalone nix tarball";
 
   inputs = {
-    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.0.tar.gz";
-
     fenix = {
       url = "https://flakehub.com/f/nix-community/fenix/0.1.1584.tar.gz";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -17,14 +15,13 @@
     };
 
     nix = {
-      url = "github:noamraph/nix/add-nix-state-home--disable-tests";
+      url = "github:noamraph/nix/add-nix-state-home-2.23.3";
       # url = "https://flakehub.com/f/DeterminateSystems/nix/=2.23.3.tar.gz";
     };
   };
 
   outputs =
     { self
-    , nixpkgs
     , fenix
     , naersk
     , nix
@@ -34,6 +31,8 @@
 
       supportedSystems = [ "i686-linux" "x86_64-linux" "aarch64-linux" ];
 
+      nixpkgs = nix.inputs.nixpkgs.legacyPackages;
+
       forAllSystems = f: nixpkgs.lib.genAttrs supportedSystems (system: (forSystem system f));
 
       forSystem = system: f: f rec {