I've heard a few things in the past concerning this subject. Nothing concrete, just thoughts.
Like, we take the ten plagues of Egypt as literal
so why not the book of Revelation?
Also, John was speaking of things he was seeing in the 1st century that belong to the 21st possibly 22nd century. So, how could he relate what he was seeing from the future into 1st century tounge for them to understand it?
Rev 16v21, 'And great hail from heaven fell upon men, each hailstone about the weight of a talent...
Hail does literally fall from heaven, but our disbelief is the size of the hail, a talent, which is about 100 pound weight.
Most have probably seen in the news of hail that has smashed through car windows and injured people. They were only the size of baseballs.
In Daniel, 12v9 Daniel is told, ...'Go your way, Daniel, for the words are closed up and sealed till the time of the end.'
In Rev 22v10 we are told, ...'Do not seal the words of the prophecy of this book, for the time is at hand'.
If that was spoken 2000 years ago, how much closer to the end are we now?
Rev 22v11 is, for me, telling us it is too late to change, the judgment is set.
You know what, literal or otherwise, Revelation is happening and will happen.
God bless.