I've been doing light tests and so far it doesn't seem to matter with anything I've tried so far
These are lentils at 6 days, the one was covered with a sock. They're only a little bit shorter, but very visibly less green. Taste is the same I think.
The second one is sunflower microgreens. Both soaked overnight. For the ones in the tray, I followed a bunch of rules like weight, keeping in the dark for a certain amount of time, using a prophylactic spray and conditioned water. The ones in the bucket I just chucked in some soil very densely (I had soaked way too many), watered every few days with the hose, and left it in a few hours of direct sun (so the height of the bucket shaded it when they were shorter.)
The tray are probably a third of the height and leaves are much smaller. The ones in the bucket are very tall, some leaves are much bigger, a bit crunchier, easily survived the high density, no mold (I have already eaten them and not gotten sick), the hulls came off much sooner and easier and they taste a bit less bitter.
I've also done chia seed microgreens with shaded light and no light until germination, and the ones left out might have even germinated a bit earlier. End result was the same, they were just as delicious as each other. I had a seperate at chia experiment where one had drainage and it didn't matter (no surprise since they're gelatinous.)
I'm going to keep doing experiments, let me know if y'all are interested to see the results, and even if you have any ideas I should try!