But the first few chapter do deal with the things which are "at hand". They are the letters to the seven churches. Those are the words they were expected to hear and to keep.
Notice that the book deals with the past, present and future:
Write the things which thou hast seen, and the things which are, and the things which shall be hereafter; (Revelation 1:19 KJV)
The last word which is translated "hereafter" is literally translated as "after these things". So the book is to be read in its current context for those who are in receipt of it in 96AD when it was written and it is also written for the benefit of those who came after so that we could recognize, hear and keep the words of prophecy of those things which occurred "after these things."
So the book deals with what was, what is, and what is to come. It will continue to have relevance to all who read it until "that which is perfect" is come.
Is there a fragment left of the original book of Revelation?
Carbon dating could work. Pretty accurate within a couple of thousand years.
Indeed, and there is no reason, at least in the context of the book, to artificially apply "at hand" to some of the material and not the rest.
Also, we not only have the "at hand" statement, we are also told these are things that "must shortly take place" (v. 1:1). So, some of the things were a present reality, and some things must take place in a relatively short period of time from the hearer's standpoint.
The same idea is reinforced at the end of the book, where the seer is told, "And the Lord God of the holy prophets sent His angel to show His servants the things which must shortly take place." (22:6).
So we have the entire Revelation bracketed by these time statements indicating that the entire book, not just portions, has immediate bearing on the the 1st century audience.
Whether or not all the material was fulfilled in the 1st century needs to be discerned by carefully comparing Scripture with Scripture. For example, I think Rev. 20 about the "thousand years" is a telescoping of the entire gospel period. And I think chapters 21 and 22 are a vision of reality after the second coming in eternity future. But the details in the majority of the book is about things that had immediate impact on the lives of the audience in that time.
"Blessed is he who reads and those who hear the words of this prophecy, and keep those things which are written in it; for the time is near."