I don’t think it would fall under invincible ignorance (since everybody was ignorant of Jesus then, they had not rejected him or the church).
That gentiles were judged by how they followed the law of God in their hearts is from one of Paul’s epistles but I don’t know chapter and verse.
One of the outer courts in the temple in Jerusalem was for the gentiles to pray to God. I think it was called the court of the gentiles. It was the one where Jesus overturned the tables because the temple was supposed to be ‘a house of prayer for all people’ but they were using that court for commerce. So God had not abandoned the gentiles who would pray to the God of the Jews.
Also, Melchisedec who offered the sacrifice of bread and wine when David’s army was victorious wasn’t a Jew but he worshiped the One God.
Noah and his family were not Jews but he was considered righteous.
I’m sure the Catechism says something about this. Good luck.