Jesus is speaking to his chosen people the Jews.
He is reassuring them that they will receive the Kingdom on Earth as promised, when Jesus returns, see, “I come only to the lost sheep of Israel” Matt. 15:24!
This promise is made to the Jews despite their treachery, as seen in the prophets, and summarised in Malachi!
Peter, you will remember, denied his Lord 3 times; as Jesus was being led away to execution!
He was told 3 times to 1)” Feed My Lambs”; 2) “Tend My Sheep”; 3)“Feed My Sheep”! These were after each of his denials!
You will also remember that Peter was asked to reach out to the Gentiles whom he considered unclean, (Acts 10), but he was reluctant, even when asked by the Spirit of God! (“I have sheep not of this Fold”, John 10:16).
Because of his reluctance as a Jew to reach out to Gentiles, he had been given the task to “shepherd” the Jewish “Lambs and Sheep”, in which function he was comfortable and Paul was the main Apostle to the Gentiles!
Peter is here writing to “the Elect sojourners of the dispersion”, Potus, Galatia, Cappadocia, Asia, and Bithynia, with encouragement and exhortations.
He is following the instructions of Jesus in the “feeding and Tending” of Jesus' sheep; “the Elect of Israel”. (“I Come only to the lost sheep of Israel”, Matt. 15:24). That applied only up to the time that Israel finally rejected Jesus, see Acts 28: 25–28; after which the Gentile became the first priority with the Jews “Lo-Ammi”. In the probably near future, that status will reverse, (Romans 11:25), and the Jews will again become “Ammi” (My people), but not until Zech.12:10 has been reached!