In Revelation chapters 7 and 14 there it talks about the 144k but says nothing of them being kings and Priests. In Revelation chapter 5 and 20 it mentions ones being kings and judges, but if you notice in chapter 20 verse 4-5 it talks about martyrs coming to life judging and reigning with Jesus, not the 144k specifically. In verse 5-6 talks about the first Resurrection and that all that share in this first Resurrection will be Priests of God and of Jesus and they will reign for a thousand years.
So notice in Revelation chapters 7 and 19 a great crowd is mentioned being alive standing before the throne standing at the same time as the 144k are mentioned. So since this great crowd is present then doesn't verse 6 of chapter 20 apply to them as well. 'Blesses and holy is the one who shares in the first Resurrection! The second death has no power over them , but they will be Priests of God and of the Messiah, and they will reign with him for a 1000 years.
When Israel was delivered out of Egypt the nation was called a kingdom of Priests and a Holy nation.
So all who are resurrected in the first Resurrection and those who make it through the great tribulation will be a nation of Priests and will reign with Jesus not just the symbolic numbered 144k.
Please correct me if I am wrong.