"One example is R.Yehuda Aryeh of Modena (1571–1648). Rabbi Modena served on the Bet Din of Venice and authored many important works, including his commentary on Ein Yaakov entitled Beit Lehem Yehuda. As a respected rabbi and a member of the Bet Din, R. Modena responded to many inquiries about his rulings on various halakhic questions. However, one response of R. Modena dealt not only with a halakhic question, but also with an event that seems to have occurred frequently. R. Modena wrote that “a Rabbi Yitzhak Gershon12 would not once or twice, but every week berate [R. Modena] for standing with his hat in his hand [bareheaded].”
Rabbi Modena would stand outside the local synagogue speaking with people, all the while without a yarmulke, and R. Yitzhak Gershon would chastise him for doing so. R. Modena justified his practice and commented that “the majority of Jews in Italy [do not wear a yarmulke]” as well. He also noted that Italian Jews “dress differently [than other Jews], grow their hair long, and their custom is to remove their hats when greeting important people, as this honors them.” Indeed, when R. Modena’s Historia de Riti Hebraici, History of Jewish Rites, was published in 1637, the portrait of R. Modena on the
cover displayed him bareheaded."
Source that contains sources Yarmulke: A Historic Cover-up?
There are also other Sephardic people who were big, but could you call them gedolim? i don't know. If someone made their own siddur that was used by an entire country (Such as the Farhi siddur for Egyptians) would you say he was a gadol?
Dr Hillel Farhi