>>9897781as someone who did lots of research for pic related, basically there is no real consensus on Zero colors. it's even worse than people shitting their pants over 4B0 and other Soviet "greens" for their tanks.
pic related is an A6M2a (Type 11), which was the first production model and was flown first in China. the original paint color is covering the wing roots and most of the fuselage. There is significant evidence to indicate that these Zeroes were stored out in open-air hangars in China, with tarps covering most of the plane but not getting the wingtips or tail. the sun bleached the color out and made it a lighter green-gray.
for later A6M2bs (Type 21; think Pearl Harbor/Coral Sea/Guadalcanal/Midway) the entire plane was more gray-green, as they would sit out on the deck and spend lots of time in the air, and were never partially covered like the 2as were.
as far as the exact shade, you can fuck around and do whatever you want, there is no one clearly specific and unique pigment the Japanese used. you can just use an off-white gray if you want, or use one of those green- or light brown-tinged ones if you want.
