Ask HN: How do you get a Kid started with Hardware, rasberry pi's etc.

My kid bro (lots of years between us) recently started getting interested in hardware and electronics. Though he showed signs when he was way younger but since he started taking science classes in school, it ignited his passion, he has almost fixed every electronic in the house. He built some cool stuff with rotors, rechargeable mobile fans some other kids stuff and he's getting really addicted to this thing. I really would love to encourage him and would like him to get started with hardware stuff like Arduino boards, raspberry pi's. He's particularly into drones and always dreams of making his own drone. So for a kid about 15 years old, how do I get him started in the world of hardware. I myself am a software developer about 5+ years and don't really know much hardware.

P.S: My kid bro even picked up JavaScript after a few months after I told him he could program drones with it(not sure if it's true, read it up somewhere). I really do want to encourage him.