Can DeclareLaunchArgument accept dictionaries?

edit

Problem (TL;DR)

ROS2 uses the DeclareLaunchArgument object to create launch parameters that can be overwritten by command line or an including launch file. I know you can use this with parameters that are strings (incl filepaths), bools, integers and floats. But I want to know if it is possible to input dictionaries as well. I haven't yet found a way to do this, and I'm not sure if it's possible.

Problem (in full)

Problem described as above. So far I've tried in ROS2 Foxy, and I haven't yet found anything that would lead me to believe this is explicitly possible in Galactic. The example I'm working with looks something like this:

// In including_launch.py
launch_description = IncludeLaunchDescription(
    PythonLaunchDescriptionSource(["~/some_package/launch/included_launch.py"]),
    launch_arguments={
        params={'num' : 1234, 'bool' : true, 'str' : "hello" },
    }
)

// In included_launch.py
params = LaunchConfiguration('params')  
params_declare = DeclareLaunchArgument('params', default_value={})

node1 = Node(
    package="some_package",
    ...
    parameters=[params]
    ...
)

If I try this example as-is, I get the following warning:

[WARNING] [launch_ros.actions.node]: Parameter file path is not a file: numboolstr

If I try turning the dictionary into a string inside the IncludeLaunchDescription call, the dictionary doesn't get mangled, but DeclareLaunchArgument still doesn't like it:

[WARNING] [launch_ros.actions.node]: Parameter file path is not a file: {'num' : 1234, 'bool' : true, 'str' : "hello" }

I've been reading through examples and source code to see if this can be achieved, but so far haven't found anything that works.