multiService defines a few options defaults like enable, namespace and dataDir, which can reasonably expected to be defined by all the services.

I propose to also include depends_on here.

Why?

• Often we end up splitting depends_on config for a service away from the service config, see

  {
    open-webui."open-webui1" = {
       enable = true;
        …
    };
  
    # Start the Open WebUI service after the Ollama service has finished initializing and loading the models
     settings.processes.open-webui1.depends_on.ollama1-models.condition = "process_completed_successfully";
  }

  (code snippet from example/llm)

  If this proposal is implemented, it can be changed to:

  {
    open-webui."open-webui1" = {
       enable = true;
       depends_on.ollama1-models.condition = "process_completed_successfully";
        …
    };
  }

• depends_on is an option almost always used while defining complex service dependency relationship.