Summary
Congratulations! By reaching this point, you have completed the AR project and six other projects: first-person 3D games, 2D adventure games, space shooters, AI, machine learning, and virtual reality.
In this project alone, you've learned the foundations of AR development. You now know how to detect planes (and other features) in a real-world environment, extract information from the detected planes, and use it to spawn virtual objects. You've taken advantage of the tools offered by AR Foundation to create an AR game that can be played on Android or iOS. The game is easy to debug, as you can see in real time when Unity has detected a plane, the size of the detected plane, and its location in the world.
You then extended Unity's offerings by writing custom scripts to extract the plane data generated by Unity and make it accessible to any script that subscribes to updates. You designed a placement marker and object spawn script that uses this information...