I’ve personally tracked my sound to the roller/pin interface, best as I can tell. When I do a fresh treat of SS, the roller has little play because there is wax between the two taking up space and acting as a cushion. The more I ride and the more wax is pushed out of the pin/roller area and the more loosely the roller moves, and the noise increases.
I don’t really agree with the whole surface oil thing, because if that was true then a freshly waxed chain with the rollers wiped clean on the outside would be loud.