How to access the runtime value of a LaunchConfiguration instance within custom launch code (injected via an OpaqueFunction) in ROS2?

edit

I'm trying to add some dynamic behavior into my python launch file(s) that depends on the runtime value of a/few LaunchConfiguration object(s).

For example, I have a yaml_file_path argument:

def generate_launch_description():
   yaml_file_path = LaunchConfiguration('yaml_file_path')
   yaml_file_path_arg = DeclareLaunchArgument('yaml_file_path')
   ...

The yaml file contains a list of entities that I need to generate IncludeLaunchDescription instances for, which will be returned by my generate_launch_description() api. For example:

#
# Only required for launch processing. These are not node params.
#
module_a:
   prefix: <some folder path>
   ...
module_b:
   prefix: <some other folder path>
   ...

I understand I need to define and return an OpaqueFunction within my generate_launch_description() method, as below:

def generate_launch_description():
   yaml_file_path = LaunchConfiguration('yaml_file_path')
   yaml_file_path_arg = DeclareLaunchArgument('yaml_file_path')

   ...
   variable_includer = OpaqueFunction(generate_variable_include_list, ...<???>...)     # <<<<<<< ??? <<<<<<<<

   return [
       yaml_file_path_arg,
       variable_includer,
   ]

The generate_variable_include_list() method injected above generates a module_includes containing the IncludeLaunchDescription instances for each item in yaml file:

def generate_variable_include_list(context: LaunchContext, yaml_file_path: str) -> List[LaunchDescriptionEntity]:
   settings: Dict[str, Any] = parse_yaml_file_to_dict(yaml_file_path)

   module_includes: List[IncludeLaunchDescription] = []
   for (key,value) in settings.items():
      module_includes.append(
         IncludeLaunchDescription(
            PythonLaunchDescriptionSource(
               PathJoinSubstitution([settings[key]['prefix'], "module.launch.py"])
            ),
            launch_arguments=[...]
         )
      )
      module_includes.append(
         LogInfo(msg=(["\tIncluding file: ", PathJoinSubstitution([settings[key]['prefix'], "module.launch.py"])]))
      )
   return module_includes

... but, I can't seem to find documentation about the following:

• how to accept the yaml_file_path into this generate_variable_include_list() function above? (Specifically shown with the <???> comment). I mean, what type is the argument supposed to be? That is, should I be passing in the LaunchConfiguration object as-is, i.e, yaml_file_path, or some post-processed version of it?
• how to use that yaml_file_path value in that function? That is, since it is an asyncio future, how do I access the resolved (runtime) outcome of that LaunchConfiguration instance within my generate_variable_include_list() method? Should I invoke the perform() API on the object, or would that cause redundant evaluation of the associated future? Is there any cache that I can lookup instead, at runtime, for the resolved value of this entity?
• And, in a general sense, what if the entity in question was any LaunchDescriptionEntity object, not just a LaunchConfiguration, and I wanted to obtain its resolved/future value in my OpaqueFunction above?

Some sample code, wherever applicable, would be greatly appreciated.