GitHub - fire1ce/raspberry-pi-power-button: Control Raspberry pi with physically attached button. Wake, Power Off, and Restart (Double Press) . Python3 script runs as a service with easy installation.
GitHub - Howchoo/pi-power-button: Scripts useful for the Pi power button
How to Use a Switch to Turn On and Off the Raspberry Pi - Circuit Basics
Adding a Switch » Raspberry Pi Geek
Raspberry Pi Safe Reboot and Shutdown Button - SparkFun Learn
Add an off-switch to power down your Pi — The MagPi magazine
Raspberry Pi Shutdown/Reset/Start Button
RetroPie Shutdown and Startup Switch – The Easy Way – Retro Pi Cart