Nice remark, and expected. I did some research into this some time ago. We were looking into "bio-light" using luciferase (the mentioned firefly protein). The thing is that that protein emits one photon for 1 ATP (fuel) molecule. The amount of ATP needed to make a 200 lumen plant, is kilograms per day. Completely unfeasible.
We concluded that indeed "green tinted moonlight" was about feasible, maybe not even. Seems like now they have a better way, too bad there are no details.
Given the human eye's sensitivity, I think it's a good first step.
In a dark room with fully-acclimated eyes, they definitely glow.
Mine are still perking up from shipping, so we'll see what output they finally achieve, but people forget you can see in a room lit by a single LED. It doesn't take much to be a night-light.
We concluded that indeed "green tinted moonlight" was about feasible, maybe not even. Seems like now they have a better way, too bad there are no details.