I found it a bit frustrating trying to set up the chroma key using the Blackmagic Design ATEM Software panel. Trying to change the values using the mouse while looking at the preview monitor was not very efficient.
So I used a MIDI device that has some rotary encoders and PowerShell to make the adjustments. See the video below for a demo
Using this almost made it fun playing with the options.
The Behringer CMD DC-1 seems to be on special at https://www.bhphotovideo.com/c/search?Ntt=cmd+dc-1
This was automated using Windows PowerShell but could have just as easily been done with JustMacros.
You can find example code for this here… https://gist.github.com/imorrish/5614d4369ca111f7096aff31d27e4d98
Description of the chroma key values for Hue, Gain, Y Suppress, Lift and Narrow from the ATEM manual: