True achdus and shalom/peace doesn’t have to mean that we’re dancing together and hugging each other all day everyday. When ehrliche yidden accept other ehrliche yidden’s right to daven their nusach and go to their respective manhigim for guidance and/or blessings, that is the best achdus.
Rav Zalman Brizel ZT”L of Yerushalayim once said (I’m paraphrasing, not necessarily quoting) “My Rebbe doesn’t have to be the biggest Rebbe. He’s MY Rebbe”.