The Big Red Button is technically a keyboard with a single button. What that button is, is up to the implementation. It can be an actual keyboard key, a
Turn your ProMicro into a USB Keyboard/Mouse - SparkFun Electronics
Arduino UNO FAQ, Arduino Tips, Tricks, and Techniques
How to Set Up a Keypad on an Arduino - Circuit Basics
Effect switcher and relays - EEPROM question - Programming Questions - Arduino Forum
OneKeyBoard · volzo
Let's get on board: how to make a one-button USB keyboard - CRAFT
Turning An Arduino Into A USB Keyboard
Use the Arduino Keyboard Library for automating simple tasks
Walktime Blog #26: The Big Red Button
Button Mouse With XIAO : 7 Steps (with Pictures) - Instructables
How to Build an Arduino Keyboard (Electronics and Code Explained
A Big Red Button Acting as a Keyboard Using Arduino