I believe there's an example of something similar happening when fertilization of an egg occurs. There's a zinc reaction which creates "flash" of visible light.

Animals (and plants? Bio 101 was a long time ago) use ATP for a lot of their metabolism and phosphates are pretty well known for emitting light as they react.

That sounds cool. I was able to find this press release about a "zinc explosion" that's been documented in human fertilization

https://news.northwestern.edu/stories/2016/04/radiant-zinc-f...

I didn't yet have the patience to go through the original research papers to see what the manner of detection was (I've had a couple of drinks this evening), but the phrasing of zinc "sparks" suggests emitted photons. On the other hand, the fact they're talking about zinc rather than photons suggets they're talking about detecting ion transfer rather than photon emission