How to set up meta launch file in ROS2? (the proper way and with namespaces)

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Dear ROS community,

I am working on a project where I want to have a single launch file that starts all sub-modules. I have a launch file for each sub-module already as this makes it easier to test them individually. So I want to have a launch file that calls other launch files instead of executables directly. From what I understand, this is called a meta launch file right?

I already figured out a solution but when I compare it with other projects on GitHub such as Turtlebot 3 or the Hustky on their foxy-devel branch, my solution looks different and I wonder if I am doing it "the proper way"?

My current solution is the following:

from launch_ros.substitutions import FindPackageShare

from launch import LaunchDescription
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import PathJoinSubstitution, TextSubstitution


def generate_launch_description():

    return LaunchDescription([
        IncludeLaunchDescription(
            PythonLaunchDescriptionSource([
                PathJoinSubstitution([
                    FindPackageShare('leorover_realsense'),
                    'launch',
                    'd455_launch.py'
                ])
            ]),
        ),
        IncludeLaunchDescription(
            PythonLaunchDescriptionSource([
                PathJoinSubstitution([
                    FindPackageShare('leorover_imu_filter'),
                    'launch',
                    'imu_filter.launch.py'
                ])
            ]),
        ),
        IncludeLaunchDescription(
            PythonLaunchDescriptionSource([
                PathJoinSubstitution([
                    FindPackageShare('leorover_rtabmap'),
                    'launch',
                    'realsense_d455.launch.py'
                ])
            ]),
        )
    ])

Also, I would like to know how I can launch all these nodes under the same namespace in ROS2 since I will run the same launch meta launch file on different (identical) robots and they should not have namespace collisions. I could only find solutions with launch files that call directly executable like the following:

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, SetEnvironmentVariable
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node  

def generate_launch_description():
parameters=[{
    'frame_id':'realsense_camera_link',
    'imu_topic':'/rtabmap/imu'
}]

remappings=[
    ('rgb/image', '/realsense_camera/color/image_raw'),
    ('rgb/camera_info', '/realsense_camera/color/camera_info'),
    ('depth/image', '/realsense_camera/depth/image_rect_raw')]

return LaunchDescription([

# Nodes to launch
Node(
    package='my_robot', 
    executable='my_node2', 
    output='screen',
            namespace="my_namespace",
    parameters=parameters,
    remappings=remappings),

Node(
    package='my_robot', 
    executable='my_node2', 
    output='screen',
            namespace="my_namespace",
    parameters=parameters,
    remappings=remappings,
    arguments=['-d']),
])

I could not find an example of how to apply the namespace on the meta launch file and I don't know if my meta launch file is done the proper way like this. Any input on this would be highly appreciated.

With kind regards, Dave vdMeer