magit-section-forward is the function that gets called on pressing n (i.e. cursor down in magit). If you want to find out which function is called on a particular key press, you can press: C-h k and then press the key/keys you want to know about.

If you want to see what magit-section-forward is doing, you can put a debugger on it by pressing C-u C-M-x on that function. After that, when you press n in magit status buffer, you will be able to step through in magit-section-forward.

C-h k with evil only shows evil-next-visual-line

so I'm guessing magit-section-forward is attached via advice or some other hook

Maybe. I’m not very familiar with evil. I use normal Emacs.

yeah, evil has plugins for other special modes to allow evil motion keys across the board, so not sure how it re-routes the movement keys to the evil commands, or where to even find them

Ah, I see.