You're reading the documentation for a version of ROS 2 that has reached its EOL (end-of-life), and is no longer officially supported. If you want up-to-date information, please have a look at Galactic.
Examples and tools for ROS1-to-ROS2 migration
Examples of node/component level migrations
Examples of system level migrations
Turtlebot has been ported to ROS 2 https://discourse.ros.org/t/tb3-introducing-ros2-tutorials/5959
Launch File migrator that converts a ROS 1 XML launch file to a ROS 2 Python launch file: https://github.com/aws-robotics/ros2-launch-file-migrator
Amazon has exposed their tools for porting ROS 1 robots to ROS 2 https://github.com/awslabs/ros2-migration-tools/tree/master/porting_tools