How to see topic from camera in iris drone

So my issue is that i followed the setup for ROS 2 with PX4 (in particular ros-foxy), and i was able to perform the offboard example, now i wanted to add an camera to the iris drone and visualize the topic related to it ; i added the camera by modifing the .sdf file of the iris and also tried with the plane model that has a camera and with Qgroundcontrol i can see the video , but there are no topics relate it to it . Users online says that you have to launch the simulation using ros in order to see the camera topic but i didn’t understand how can i achive this so i was wondering if someone could give me a little clarification about how should i set up a simulation with a PX4 node using ROS that allow me to see the camera topic or any other topic related to sensors attached to the vehicle