so use

age.secrets = {};

in my home.nix?

how would I access those variables in other parts of my home.nix

again I'm used to the config.age.secrets syntax

seriously? my lsp says it can't find config which checks out because it's not an input to the home function

okaaaay, and I can access the path from that I think, config.age.secrets.whatever.path

builtins.readFile?

generally speaking, services that handle secrets will let you pass them as a file (as in, you enter the filename)
like my listenbrainz-mpd config

services.listenbrainz-mpd = {
  enable = true;
  settings = {
    submission = {
      token_file = config.age.secrets.listenbrainz-mpd-token.path;
    };
  };
};

and sometimes they don't and you have to bend over backwards to find a way to inject them in another manner! (I feel icky about this script I wrote)

    xdg.configFile."mcphub/servers.json" = {
      source = jsonFormat.generate "servers.json" {
        mcpServers = {
          github-mcp = {
            command = lib.getExe (
              pkgs.writeShellApplication {
                name = "github-mcp-server";
                runtimeInputs = [pkgs-unstable.github-mcp-server];
                text = ''
                  GITHUB_PERSONAL_ACCESS_TOKEN=$(cat ${osConfig.age.secrets."github-mcp-token".path})
                  export GITHUB_PERSONAL_ACCESS_TOKEN
                  ${lib.getExe pkgs-unstable.github-mcp-server} "$@"
                '';
              }
            );
            args = ["stdio"];
            env = {};
          };
        };
      };
    };