If he loves to build things or learn how they work, you definitely want to pursue physical science or Physics. In following with the theme of choosing authors or teachers who love their topic CM style I could make some recommendations.
https://learnscience.academy/ Conceptual Academy started with Paul Hewitt who wrote a very well known and loved Conceptual Physics book. They added videos here https://www.youtube.com/channel/UCzfPYsDenQo0XYHq4SmfG0Q
which you can access for free but having the videos, plus homework questions, plus reading assignments all put together for you is worth a lot. I just started the Physical Science with my third high schooler so I can only really review the first part of it. This is not a Christian curriculum but it isn’t really an issue with forces and motion and such. Biology and Geology is where you will find the most disagreement with secular textbooks.
My oldest and youngest sons have taken classes at Potter’s School and their reviews range from fairly good to good. I didn’t think my third child could keep up though as he is very active, hands-on and doesn’t really like school so we chose the Conceptual Academy for him. He can do it in 12 months instead of 9.
I would also recommend Great Courses. Once again these aren’t Christian so you probably won’t like the Biology and Geology but the “How Everyday Things Work” or what I’m currently watching with DS 3, “Understanding the World’s Greatest Structures” is really good and has no controversial stuff. It is stuff you would learn in college engineering but they don’t make you do all the math which is really the hard part so you can still get the concepts.