Since Nog lives on a Bajoran station, if this were a textbook case of cultural assimilation, the question might be expected to hinge upon his taking on traits from Bajoran culture. He doesn't. He chooses to join Starfleet. As far as we know, there's nowhere in the Federation where cultural assimilation in the textbook sense could apply to a Ferengi, although this doesn't mean that you couldn't make a case with another species. (I'm not denying that cultural assimilation COULD be applied to the Federation in some context, I just don't find it applicable to Nog's circumstances.)
Yes... but lets take another look... Nog went to a school run by Star Fleet person making up her own lesson plans most likely favoring Star Fleet themes. His best friend is a son of the commander of DS9 a Star Fleet officer. His dad works for DS9 which is Bajoran but controlled and operated by Star Fleet. Everyone on the station knew Star Fleet was the dominate cultural presents on the station... So maybe Nog was classically assimilated by Star Fleet... bubblelike... a thought...