Apple’s accessibility tools bring us tantalisingly close to the amber monitor look. All we need is the already available grayscale filter, but with shades of amber rather than shades of grey. I’m sure there’s a low-level API that makes it possible…
I used to do something like that when I was developing b&w photos in my room. I changed the color balance somehow to block green and blue to have a red only display. This way I could use a timer app on the computer for developing photos. (I also had to turn the brightness of the monitor down pretty far, just the red software filter apparently wasn't enough)
https://github.com/Swordfish90/cool-retro-term
QED :)