Starting point for kids/teens?

Hi! Soon I’ll have my little nephew (13) in my company to check out software development for a week. I’m working with large industry machines in real time Linux systems, so obviously I’d show him my test machine and if the customer agrees, I can show him some robots as well. Also, he will get some crash course in computer basics. He is an avid gamer - although not really good with computers. I’ve gifted him a still nice laptop with Linux and Steam installed 1-2 years ago and he happily played Minecraft, but after some time he went back to his Switch 2. Now he uses my Steam Deck - although that doesn’t make that much of a difference… I’d like to give him something fun as an exercise, that’s is early rewarding. Perfect would be, if he could code himself a little computer game, but that’s completely out of my normal work stuff and I don’t know what good options are available. I guess starting with C++ and an Unreal engine or similar is more than an overkill. Is there something, that is teaching the basics and gives rather quick rewards, which can produce a little something after 2-3 days? Thank you all in advance!