In some projects with Arduino/Python, a full-featured “Keyboard” instead of a membrane keyboard, is needed. there the Mini Wireless Keyboard is a good solution, but sometimes still too big.
This mini Blackberry Q10 keyboard could be a good solution. JoeN, from the Arduino forum, taken us a good suggestion, and also the related usage examples, to use this mini keyboard in the project(https://forum.arduino.cc/index.php?topic=355709.0).
The keypad is a bitch to the interface because it uses a 0.4mm pitch connector on flat flex, not really all that hobby friendly. And it worked pretty well as hobbyist repellent as near as I can tell, until now. I have been able to build an adapter board to convert the appropriate connector to DIP, interface it to an Arduino, determine the pinout, and create a short demonstrator sketch to prove the interface and allow the user to type text out to an OLED.
They're also the connection breakout board design and Arduino codes, for reference. And also some detailed explanation at Adafruit Blog.