What John says he saw in his vision was the ark of the covenant but he would not be referring to the ark of the old covenant which was, of course, an earthly copy of what exists in heaven. The covenant that John would be referring to is the new covenant and its ark is not a wooden box covered in gold. If you want to pursue the vision's image then read on; the next thing that John sees is a woman dressed in the sun and standing on the moon with twelve stars as a crown on her head.
Then God's temple in heaven was opened, and the ark of his covenant was seen within his temple. There were flashes of lightning, rumblings, peals of thunder, an earthquake, and heavy hail. And a great sign appeared in heaven: a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars. (Revelation 11:19-12:1)
What did this woman have to do with the temple and the ark of the covenant you might ask, and why is she clothed in the sun (a gold far more bright than any earthly gold) and why does she stand on the moon and have a crown of 12 stars? In addition this woman is not the centre of this continuing vision because she is pregnant and her child draws the apostle's eye thus
She was pregnant and was crying out in birth pains and the agony of giving birth. And another sign appeared in heaven: behold, a great red dragon, with seven heads and ten horns, and on his heads seven diadems. His tail swept down a third of the stars of heaven and cast them to the earth. And the dragon stood before the woman who was about to give birth, so that when she bore her child he might devour it. She gave birth to a male child, one who is to rule all the nations with a rod of iron, but her child was caught up to God and to his throne, and the woman fled into the wilderness, where she has a place prepared by God, in which she is to be nourished for 1,260 days. (Revelation 12:2-6)
Of course there is no vision of tablets of stone with the ten commandments in this passage (or any other passage set in heaven in either testament) so the art work in brother Lysimachus' very long post does not correspond to anything mentioned in Revelation. The following image, imperfect as it is, is far closer to what John saw than was the image that brother Lysimachus gave.
The juxtaposition of the ark of the covenant and the woman is interesting, it is also interesting that this woman "contained" a baby, the child born to rule the nations with a rod of iron. There is another passage a little later in Revelation that also speaks of ruling the nations with a rod of iron.
Then I saw heaven opened, and behold, a white horse! The one sitting on it is called Faithful and True, and in righteousness he judges and makes war. His eyes are like a flame of fire, and on his head are many diadems, and he has a name written that no one knows but himself. He is clothed in a robe dipped in blood, and the name by which he is called is The Word of God. And the armies of heaven, arrayed in fine linen, white and pure, were following him on white horses. From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty. (Revelation 19:11-15)
The contents of this woman is, it appears, Jesus Christ and it is not surprising that the contents of the woman is the new covenant himself, because, after all, Christ's said that the cup he gave to the apostles was the new covenant in his blood and that appears to identify the new covenant with Christ himself rather with with commandments written in stone. The
testimony that gets a mention in Revelation is not the ten commandments but rather the testimony of Jesus.
Then the dragon became furious with the woman and went off to make war on the rest of her offspring, on those who keep the commandments of God and hold to the testimony of Jesus. And he stood on the sand of the sea. (Revelation 12:17)