It’s like pirating people. You wouldn’t pirate a movie!

I found khan academy to be really good. My daughter handled the JavaScript module pretty well at the age of 9. If your son is already familiar with the concept of programming and can read well enough, I’d be pretty sure he’d enjoy this

https://www.khanacademy.org/computing/computer-programming

.net core now has all the framework stuff and all runs great on Linux. C# is a really nice language.