From my understanding, it's generally considered obligatory or necessary to participate in the minhagim of your community. However, say that person, person A, travels elsewhere where the minhag is not practiced. Would it be a mitzvah for another person from that foreign community, person B, to help them in fulfilling a minhag? That is to say, if person A travels from, say, Poland to Morocco, for whatever reason (vacation, business, et cetera), would it hold any halachic value for a native of that Moroccan community, person B, to help person A in his Polish minhag?
By mitzvah, I mean is it a halacha? Not necessarily that it's a good thing or something recognized as a normative value within Jewish life.