Does the Bible contain any hint in the Gospels that God would call out a people from the Gentiles?
No, the Gospels contain no hint that God would turn to the Gentiles to call out a people for His name. Jesus never betrayed that secret, and the Old Testament prophets saw the two advents as one, not the Church Age comprised of Gentile believers.
Les teaches that all prophecy was directed to Israel, and no prophecy indicates the Church as such. Not a word is breathed in the Old Testament about this Church Age comprised of Gentile believers. Even in the four Gospels, there is never a single hint that God would turn to the Gentiles and call out a people for His name. Jesus was meticulously careful not to betray that secret, though He knew the end from the beginning. He never revealed anything kept hid in the mind of God, revealing things according to His time frame. The Old Testament prophets viewed the two advents as one, like mountain ranges seen from a distance, not discerning the valley of the Church Age between. Israel's rejection opened that parenthetical period.