The impression of green-ness can be created by an infinite combination of wavelengths and intensities. All that is necessary is for the light that hits your retina to cause the various cone cells to fire at the right rate. Most of us have three types of cone cells. Some only two. Some four. Some none. All but the last have their own interpretation of green-ness.

We think of light as having a color; but color is an artifact of our brain based upon the very rudimentary frequency sensors in those cone cells. Light, itself, is never green. Certain combinations of intensities and frequencies are interpreted as green.

Source: x.com/unclebobmartin/status/1819787895789572162