https://twinkletray.com/
Most desktop monitors have their brightness & other config exposed via the DDC (DDC?) protocol. This is a simple UI that exposes the brightness controls on Windows. Much easier than using the buttons.
You might need to go to the monitor's menu and enable DDC if it's disabled by default.
On Linux this script works for me:
sudo modprobe i2c-dev; sudo ddcutil setvcp 10 $1 &