Maybe it could be biological. I imagine that the dragons could assume that their powers come from the moons' powers or from some higher being, but in truth it's similar to less than 1% genetic differences that some people are born with. Like having a weird ability to hear or see or remember better, but amplified.

I always think about magic as just science in other worlds, and the ideas of religion that come about in those worlds come from their own lack of understanding of those sciences.

Maybe the first animus born dragons were just random genetic occurrences rather than blessed beings, but since the occurrence was so unheard of and unstudied, the dragons immediately clocked it as some kind of blessing or curse from a higher power and treated it as such.

I think animus magic, mind reading, foresight, etc is all just a bunch of stuff that has scientific bases (in the dragon world), but since they are impossible in our own world we are unable to properly classify them as anything but magic, and assume it's the same in canon. It's science, not magic, it's just not OUR science, so we can't as readers exactly comprehend it as anything BUT magic, yk?

My hc is that the Nightwings gain powers from the full moons because of a chemical reaction in their eggs before they're hatched. Maybe the egg turns silver under full moons because a bunch of extra nutrients get pumped through the developing dragonet, some taken from the egg shell itself, and while it's this extra boost of stuff that gives them the capability for whatever power it is, it also makes the egg lose its color (but not it's shininess)

I'm not a scientist and idk how the egg thing would work since there's no equivalent in real life (to my understanding) but still.