I made a replacement for my Razer Tartarus V2. It is a gaming focused Keypad with 21 buttons, a scroll wheel and an analog joystick.
I originally used a PyBoard but had to switch to a Teensy after finding some of the PyBoard's limitations. I also couldn't get MicroPython working well on the Teensy so I had to stick with Teensyduino
Still, I got it working and I wrote some monitoring software in Python that runs in Windows and sends new profiles to the Teensy when different game processes are found. I am working on the web interface now to make it easy to change out mappings for different games. Full details are on the github page.