I would first start him on some guided C++ projects that illustrate basic syntax, data structures, explain libraries, pointer, how memory works, etc. I wouldn't spend a lot of time here. Some simple but neat console games that also showcase some math coolness (like guess a number between 1-100, then say you can guess it in 7 or fewer guesses).
This is how I learned, and was very helpful in understanding some of the why and how of programming. This gave me a deeper understanding of what was going on when I was introduced to easier languages. It also gave me enough understanding to ask how things worked in the easier languages.
After that brief learning period, then I would put him Python. There are lots of powerful libraries and it's easier to build more advance projects. There is also great support for physical stuff like Pi hats if he wants to so robotics, sensors, etc.