"No man has seen God at any time; the only-begotten god who is at the Father’s side is the one who has explained Him."
It may be possible, however that the prophets may have seen aspects of him such as found in Ezekiel 1:26-28
"Above the expanse that was over their heads was what looked like a sapphire stone, and it resembled a throne. Sitting on the throne up above was someone whose appearance resembled that of a human. I saw something glowing like electrum that was like a fire radiating from what appeared to be his waist and upward; and from his waist down, I saw something that resembled fire. There was a brilliance all around him like that of a rainbow in a cloud on a rainy day. That was how the surrounding brilliant light appeared. It was like the appearance of the glory of Jehovah. When I saw it, I fell facedown and began to hear the voice of someone speaking."
“I kept watching until thrones were set in place and the Ancient of Days sat down His clothing was white like snow, and the hair of his head was like clean wool. His throne was flames of fire; its wheels were a burning fire."
An explanation of those visions can be found in Insight from the Scriptures VII
"these descriptions employ metaphors and similes, likening Jehovah’s appearance to things known to humans—jewels, fire, rainbow. He is even described as though he had certain human features. While some scholars make a considerable issue out of what they call the anthropomorphological expressions found in the Bible—as references to God’s “eyes,” “ears,” “face” (1Pe 3:12), “arm” (Eze 20:33), “right hand” (Ex 15:6), and so forth—it is obvious that such expressions are necessary for the description to be humanly comprehensible. For Jehovah God to set down for us a description of himself in spirit terms would be like supplying advanced algebraic equations to persons having only the most elementary knowledge of mathematics, or trying to explain colors to a person born blind.—Job 37:23, 24. The so-called anthropomorphism's, therefore, are never to be taken literally, any more than other metaphoric references to God as a “sun,” “shield,” or “Rock.”
So drawing from that I am unsure whether John saw a physical form or was trying to relate in human terms what he saw. It is pretty hard to describe something to others when they have absolutely no knowledge of what it looks like or in this case relating a vision when there are no words to properly explain what you saw. Instead you try to use describing words to relate it to others. It's sort of like describing the wind. You can't see it, but you can describe things about it to make it understandable.
Moses "saw" God too. but then he left this warning to the people of Israel at Deuteronomy 4:15-18
“Therefore, watch yourselves closely—since you did not see any form on the day Jehovah spoke to you in Ho′reb out of the middle of the fire— that you may not act corruptly by making for yourselves any carved image having the form of any symbol, the representation of male or female, the representation of any animal on the earth or the representation of any bird that flies in the sky, the representation of anything creeping on the ground or the representation of any fish in the waters under the earth.
Moses said that after he had seen God in Exodus 24:9-11
Moses and Aaron, Na′dab and A·bi′hu, and 70 of the elders of Israel went up, and they saw the God of Israel. Under his feet was what seemed like a sapphire pavement, and it was as pure as the heavens themselves He did not harm the distinguished men of Israel, and they saw a vision of the true God and ate and drank.
As we do not have the proper information we then cannot make a conclusion. That is something we will have to ask God later I guess.