That particular phenomenon with the eyes closed in the dark could be something called "phosphenes" https://scienceline.org/2014/12/why-do-we-see-colors-with-our-eyes-closed/
I think I get that too, but it's hard to tell if it's that or just the colors/static from the visual snow.
As for the nearsightedness / VSS correlation - I had the visual snow way before I was nearsighted. The interesting thing is that visual snow remains sharp with or without glasses, and the static is there whether the eyes are open or closed. Latest research points to the static/noise part of it happening in the brain, rather than in the eyes.
Could be phosphenes. Think I saw that before but was never sure if it was quite right. it has a very specific look that is hard to describe. it's always red and green... sorta and flows like a lava lamp... kinda :). If I was artistic enough I'd try to draw it or something.
I also see the static regardless of eyes open or not which is one of the reasons my layman's research leads me to be pretty sure it is VSS.