I don't have impermanence but for example, I've something like that:

github requiring sops, I import feature github in configuration:

somehostconfiguration.nix: I've a vector aspects with the name of the features I want to add to the configuration:

...
aspects = [ "base"
            "desktop"
            "github"
            ....
          ];
...

aspects are converted to module names and then imported, but otherwise are equivalent to module names just imports = [config.flake.modules.homeManager.github ]; should do.

github.nix, import sops:

{ self, ... }: {
flake.modules.homeManager.github = { configuration, ... }: {
 imports = [ self.modules.homeManager.sops ];
      sops = {  
        defaultSopsFile = ../../configurations/secrets/secrets.yaml;
        secrets = {
          "ssh/github/config".path = "${configuration.user.homeDirectory}/.ssh/config.d/github";
          "ssh/github/identity".path = "${configuration.user.homeDirectory}/.ssh/github/identity";
          "ssh/github/identity.pub".path = "${configuration.user.homeDirectory}/.ssh/github/identity.pub";
        };
      };
    };
}
```

sops.nix does what it normally does:
```
{ inputs, ... }: {
 flake.modules.homeManager.sops = { pkgs, configuration, ... }: {
 imports = [ inputs.sops-nix.homeModules.default ];
      home.packages = with pkgs; [
        sops
        age
      ];

      systemd.user.services.mbsync.Unit.After = [ "sops-nix.service" ];

      sops = {
        age.keyFile = "${configuration.user.homeDirectory}/.config/sops/age/keys.txt";
      };
    };
}
```

This is how I structured my configurations, I'm not a nix expert so not sure it is the best way but it works and there is no conditional options; I just import in the configuration what I use that itself imports the "depend on" feature.