Here is another cute robot that can take your coding skills to the next level. The Petoi Bittle is Arduino IDE compatible and can be coded in C++ or Python. It had 3D puzzle parts, so you can easily put it together. Bittle is based on OpenCat, which is an open source quadruped robot platform.
This robot also supports drag & drop programming. It is compact enough to fit in the palm of your hand. You can attach a Raspberry Pi 3A+ or Zero to give this robot even more power.