You're confusing the matter. Exo 19 and 1 Pet 2 speak of the same Israel. It doesn't matter if Exo is speaking of OT Israel, and 1 Pet is speaking of NT Israel. The point is, both refer to a specific holy nation. That can only be Israel. This fact does not need to have Israel in both places refer to OT Israel, or both places to speak of NT Israel. Your adage has zero application to this.
I gave you an example. You are mentioned as being in two different places, in a house somewhere and in a back alley somewhere. If I refer to *you* in both places, this does not require that the circumstances be the exact same in both places to identify *you!* You don't need to be in a house in both places to identify you. You don't need to be in a back alley in both places to be you.
I'm at an end on this point, because you're obviously unable or unwilling to see it. Be happy with what you believe.
That's a bullet that you can't dodge.
If, as you claim, the nation of 1 Peter 2:9 is the literal nation of Exodus 19:6; then the priesthood of 1 Peter 2:9 is the literal priests of Exodus 19:6.
That's simple undeniable unassailable logic and consistency.
Of course, if logic and consistency are of no significance to you, then you can claim whatever you wish.
The overwhelming majority of recognized apologists of the true Christian Church before the 19th century who have exegeted 1 Peter 2:9, declare the holy nation to represent the Christian Church.
When Jesus told the Jewish leaders...:
Matthew 21
43 Therefore say I unto you, The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof.
...you can be assured that He was not referring to the literal nation of apostate Israel.
There was only one nation to which He could have been alluding.
The holy nation of the Church in 1 Peter 2:9.