Rev 7:14 I said to him, “My lord, you know.” And he said to me, “These are the ones who come out of the great tribulation, and they have washed their robes and made them white in the blood of the Lamb.
If we place the Great Tribblelation as the period of 66-70 AD and we understand that they are the firstfruits "unto God and the Lamb" during the 1st century then they reigned with Christ for a "symbolic" thousand years
Rev 14:4 These are the ones who have not been defiled with women, for they have kept themselves chaste. These are the ones who follow the Lamb wherever He goes. These have been purchased from among men as first fruits to God and to the Lamb.
Rev 1:6 and He has made us to be a kingdom, priests to His God and Father—to Him be the glory and the dominion forever and ever. Amen.
1 Peter 2:9 But you are chosen race, a royal priesthood, a holy nation, a people for God’s own possession, so that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light;
Peter is addressing the "diaspora" of the tribes of Israel as was James:
1 Peter 1:1 Peter, an apostle of Jesus Christ, To those who reside as aliens, scattered throughout Pontus, Galatia, Cappadocia, Asia, and Bithynia, who are chosen
James 1:1 James, a bond-servant of God and of the Lord Jesus Christ, To the twelve tribes who are dispersed abroad: Greetings.