My kid loves the idea of robots and I'm looking for kid-grade projects that an adult can help with (even carry the project a bit if they can turn a wrench or cut a wire) .

I have a physics degree, and computer science degree and I tinker, (built a few custom tools, and do a lot of my own repairs), but I have limited "robotics" experience directly.

There's lots of kits for the classic "Arm" idea, or cars with sensors, but I was wondering if others had some more free form ideas. Kits seem single purpose and not always reusable. Ideally we'd start smaller and grow our ideas without buying new kits every time, or net new components... But I could use some steering on expectations. Thanks!