One interesting effect of psychedelics that I've noticed is that they can cause the framebuffer behind my head and the framebuffer in front of my head (i.e. on the insides of my eyelids) merge into one framebuffer. It's quite an odd and fascinating state to be in!
It’s incredibly fascinating to learn about nuances between humans.
I apparently have excellent spatial awareness and reasoning. I can imagine shapes and scenes. Rotate a shape and have a good crack at sketching it from my mind.
But I would never describe this as similar to actually seeing in any way. If I had to describe what I experience after reading through a lot of these descriptions it would be "knowing". When I visualize something it's like I'm "knowing" it's shape, size, position, and etc. But it's nowhere and I'm certainly not seeing it in any way that's meaningfully similar to actual sight.
Most people are like this, with variation in the degree of vividness and control. Some people can make realistic detailed scenes, for other people it's harder and their images are often blotchy or lacking in detail and colour. I'm in the latter group.
If you don't have any of this at all and you're surprised by the whole idea, you are probably aphantasic.