For example if I want to take a visual SLAM or orb-slam repo from github and use them on a premade robot like a turtlebot3 or DJI tello.

What if it wasn't made to be use without ROS in mind? Do I just solve that by writing my own wrapper? What happens if it was made for ROS1 and not ROS2 how do I use it then.

What if it wasn't made to be used on humble is it possible for me to port it over?

How do I learn more about these sort of things? Any links to tutorials/blogs/videos would be greatly appreciated