JoyC is a rocker module designed for the M5StickC.It supports two-hand operation. Embedded STM32F030F4 main control chip, using I2C communication protocol and host M5StickC for data transmission. The range of the joystick is 0~200, there are 12 RGB LEDs under the left and right joysticks, and the bottom of the joystick is equipped with a 16340 battery base for continuous battery life.
This is a really fun toy; I bought with the RoverC to control it, but soon thereafter found other uses for it. But be warned - the example code I've found so far is sparse and only includes a simple wi-fi client interface for use with another esp32 acting as server. This is fine unless you want to use wifi on the server for other things, which is why I've started writing up a BLE interface for the JoyC (a non-trivial project). But for what it is, the JoyC is a good deal and nicely made.
Finally a universal self-programmable controller ...
Good product for controlling my RoverC. Just wish there was code to control BalaC also.