Did They Know What They Were Writing (or speaking) was Scripture When They Wrote/Spoke?

[prism]

2 Peter 1:20-21 NASB95
But know this first of all, that no prophecy of Scripture is a matter of one's own interpretation, [21] for no prophecy was ever made by an act of human will, but men moved by the Holy Spirit spoke from God.

1 Peter 1:10-12 NASB95
As to this salvation, the prophets who prophesied of the grace that would come to you made careful searches and inquiries, [11] seeking to know what person or time the Spirit of Christ within them was indicating as He predicted the sufferings of Christ and the glories to follow. [12] It was revealed to them that they were not serving themselves, but you, in these things which now have been announced to you through those who preached the gospel to you by the Holy Spirit sent from heaven-things into which angels long to look.

 

[Josheb]

Did They Know What They Were Writing (or speaking) was Scripture When They Wrote/Spoke?​

Yes. Aside from the commendable verses cited in the op, let's add,

2 Peter 3:14-16
Therefore, beloved, since you look for these things, be diligent to be found by Him in peace, spotless and blameless, and regard the patience of our Lord as salvation; just as also our beloved brother Paul, according to the wisdom given him, wrote to you, as also in all his letters, speaking in them of these things, in which are some things hard to understand, which the untaught and unstable distort, as they do also the rest of the Scriptures, to their own destruction.

By the time Peter wrote his second epistle the writings of Paul were recognized as included with "the rest of the Scriptures." (and those who distorted his writings did so to their own destruction ).

 

[EarlyActs]

2 Peter 1:20-21 NASB95
But know this first of all, that no prophecy of Scripture is a matter of one's own interpretation, [21] for no prophecy was ever made by an act of human will, but men moved by the Holy Spirit spoke from God.

1 Peter 1:10-12 NASB95
As to this salvation, the prophets who prophesied of the grace that would come to you made careful searches and inquiries, [11] seeking to know what person or time the Spirit of Christ within them was indicating as He predicted the sufferings of Christ and the glories to follow. [12] It was revealed to them that they were not serving themselves, but you, in these things which now have been announced to you through those who preached the gospel to you by the Holy Spirit sent from heaven-things into which angels long to look.

Keep in mind that that is a description of the OT. Then between the resurrection and Pentecost, they have 40 days of in-person instruction about Moses and the prophets and the message of Christ in those texts. The result is seen in the 1st talks in Acts 2-4, and then various Acts passages until ch 15.