Here is another STEM kit that lets you build a fun robot with a Raspberry Pi brain. The Freenove Big Hexapod Robot combines with your Pi 4B and other models to teach you a thing or two about coding. It can be controlled with an iOS and Android device in addition to your computer.
The kit ships with a Spider Shield for Pi, various servos, acrylic parts, camera, a HC-SR04 Ultrasonic module and a MPU6050 module. You also get the complete Python code to examine. The Freenove Big Hexapod robot comes with self-balancing, face recognition, ultrasonic ranging, and real-time video functions.