I know that Jehovah’s Witnesses are non-trinitarian, not sure about Mormons. There some other sects that are non-trinitarian, but all of them small. (But I point out that Christianity survived about 300 years without a Holy Trinity).
And I agree: the Holy Trinity is what makes Christianity quite different from Judaism and Islam. But there’s no questioning in the Christian community that Yahweh is the same entity as God the Father. That the god described in Exodus is the same god described in Luke.
Just like all muslims agree that the same entity is being described in the Bible and in the Quran, no wonder Adam, Moses, Abraham, Noah, Jesus are prophets of Islam. Even if this offshoots are wrong, they still worship the same entity.