(Nav2 for Humble)

Do it in every terminal where you will start simulation from Getting Started (Nav2 documentation):
(for PC IN LABORATORY)
export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp # for every terminal
export CYCLONEDDS_URI='<CycloneDDS><Domain><Discovery><ParticipantIndex>none</ParticipantIndex></Discovery></Domain></CycloneDDS>'
export ROS_DOMAIN_ID=123 # please use your PC number
(always)
export TURTLEBOT3_MODEL=waffle
(always)
export GAZEBO_MODEL_PATH=$GAZEBO_MODEL_PATH:/opt/ros/<your-ros-distro>/share/turtlebot3_gazebo/models

Download the YAML config file to modify & add plugins (for PC IN LABORATORY):
https://raw.githubusercontent.com/ros-navigation/navigation2/refs/heads/main/nav2_bringup/params/nav2_params.yaml

If you are working on your own PC - you can find this YAML file there:
/opt/ros/<your-ros-distro>/share/nav2_bringup/params

Command to start simulation with TB3 and Nav2 stack (warning: it will take a while to start, up to 30 seconds! remember about setting initial pose with 2D Pose Estimate):

ros2 launch nav2_bringup tb3_simulation_launch.py --show-args

ros2 launch nav2_bringup tb3_simulation_launch.py headless:=True params_file:=/path/to/your/nav2/configuration/yaml