Wireless Nunchuk
The first time I came across a Nunchuk is when I started making my Blueboy balancing robot.  Techknowtone (England) used this to control his robot and I thought this was a cool item because it allowed one hand operation of the joystick, instead of two hands required.

That version kept the "smarts" inside that converted the joystick to I2C signals which were then converted by software into radio signals to send out to the remote device.  I had a version like that but it was "kludgy" since more electronics had to be added to a box that connected to the Nunchuk via a cable.   There had to be a better way.

I gutted the Nunchuk and put in a small Pro Micro MCU with battery and HC12 radio device.  That's it!  A wireless remote control in a one handed container.