So Paul, standing in the middle of the Areopagus, said: “Men of Athens, I perceive that in every way you are very religious. For as I passed along, and observed the objects of your worship, I found also an altar with this inscription, ‘To an unknown god.’ What therefore you worship as unknown, this I proclaim to you (Acts 17:22-23)
Paul told the Athenians that the unknown god they were worshipping was the one true God.
I've noticed that sometimes people will adopt an "all or nothing" style of thinking.
that thinking leads to the conclusion that a person must worship God completely and with full knowledge or that person is worshiping a false god.
sometimes a person engaged in this style of thinking perceives themselves to be taking a firm stand for the truth.
but the people of Athens and the larger Greek culture did have some knowledge and experience of God, else why does Paul quote their poets?
as you noted, Paul says,
"What therefore you worship in ignorance, this I announce to you."
Paul is going to announce to them the true God, and he says that's what they are already worshiping in ignorance.
granted, in addition to worshipping God, they were also worshipping false gods and had many misconceptions about what God wanted.