importOverride.nix

let
  importOverride = path: replacements:
    builtins.scopedImport {
      import = importPath:
        if builtins.hasAttr (builtins.baseNameOf importPath) replacements then
          builtins.scopedImport {} (builtins.getAttr (builtins.baseNameOf importPath) replacements)
        else
          importOverride importPath replacements;
    } path;
    
  androidEnvOverride = importOverride <nixpkgs/pkgs/development/mobile/androidenv> {
    "packages.nix" = /path/to/my/replacement/packages.nix;
  };
  
  androidEnv = callPackage androidEnvOverride {
    licenseAccepted = true;
  };
in
rec { }