A simple BetterTouchTool touch bar widget that can change the color temperature of your screen with a slider.
Tap on the icon to toggle Night Shift, the color of icon is switched between white and orange based on current status.
Hold the icon to activate the slider, the number on the right is the color temperature in Kelvin.
This widget is written in AppleScript-ObjC, using macOS private framework CoreBrightness, you can check the code in \source folder, refer to Apple-Runtime-Headers for more information.
Download NightShiftSlider.bttpreset, double click to import to BTT.
You cannot replace assigned action of the icon with BTT's built-in Night Shift toggle action, otherwise, the code cannot detect the status change.
You may experience Night Shift flicking, or the icon color is not match with current status, try restart BTT.