He emphasizes that salvation comes through the grace of Jesus Christ, not through the observance of the law of Moses, and that both Jews and Gentiles are saved in the same way.
Look at what Peter preaches in Acts 10
[Act 10:43, 45 KJV] 43 To him give all the prophets witness, that through his name whosoever believeth in him shall receive remission of sins. ... 45 And they of the circumcision which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost.
These Gentiles heard and believed the same gospel preached by the twelve......Peter and the twelve preached the name of Jesus. not the cross
[Act 15:11 KJV] 11 But we believe that through the grace of the Lord Jesus Christ we shall be saved, even as they.
Peter is not teaching the grace of God that Paul preaches
[1Pe 1:13 KJV] 13 Wherefore gird up the loins of your mind, be sober, and hope to the end for the grace that is to be brought unto you at the revelation of Jesus Christ;
Peter is preaching that the nation of Israel would receive grace at the coming of Christ
[Psa 84:11 KJV] 11 For the LORD God [is] a sun and shield: the LORD will give grace and glory: no good [thing] will he withhold from them that walk uprightly.
[Gen 39:4 KJV] 4 And Joseph found grace in his sight, and he served him: and he made him overseer over his house, and all [that] he had he put into his hand.
Grace can be found in the old testament