I don't see Peter addressing whether or not people know the name of Jesus, but rather that the gospel applies to people in all nations.
That is not what Peter said. Again:
"Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons: But in every nation he that feareth him, and worketh righteousness, is accepted with him" (Acts 10:34-35).
When Peter speaks of people "fearing" God he is speaking of people believing in the existence of God and therefore fear Him. One of the meanings of the Greek word translated "feareth" is
"to reverence, venerate, to treat with deference or reverential obedience."
And this reverance toward the LORD will lead a man to obey his conscience and that is what Peter meant when he spoke of those people working "righteousness."
And since all men have the ability to believe that God exists and to obey their conscience then there is not a person down through history who cannot be saved.
And that thought is expressed here as well:
"And without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him" (Heb.11:6).
The LORD is not going to make any of His creatures without a way to escape hell.
He is not a Mad Potter who would make His vessels for the express purpose of destroying them:
"But now, O LORD, thou art our father; we are the clay, and thou our potter; and we all are the work of thy hand" (Isa.64:8).
Anyone who doesn't realize these facts do not have a good understanding of the things of the LORD.