Generally, the original non-Chassidic Ashkenazi community in Israel were followers of the Vilna Gaon. Since they were practically the only Ashkenaz presence in Israel, they were able to institute many of the Vilna Gaon's rulings in their new communities. So why is the general non-Chassidic custom in Israel to use the Nusach Sefard (not the Nusach Eidut HaMizrach, but Sefard which is a mix of Nusach Ashkenaz and Eidut HaMizrach)?
Outside of Israel, this Nusach is traditionally used by (non-Chabad) Chassidim, while non-Chassidim use the traditional Nusach Ashkenaz. Did the Vilna Gaon support using Nusach Sefard?