Here is another robot kit that introduces your kids to coding. The SunFounder PiArm is made to work with Raspberry Pi boards. It is a 3+1 DOF robot arm with 3 interchangeable parts (shovel bucket, hanging clips, and electromagnet). You can control it with a joystick or on your phone with the Ezblock app.
The PiArm is ready for drag & drop programming but more advanced users can write code in Python. It can dig, pick, place, and hold objects. This robot kit is compatible with the Raspberry Pi 4B, 3B+, 3B.[where to get it]