I can't picture the final product in my head. It doesn't exist until I make it. I can picture the semantic idea of it being done, what it would mean in the grand scheme of things, but I can't imagine the finished product. It's really kind of mind boggling to me the idea that people out there say that they can picture something front to back, inside and outside. My first thought is that they're lying to themselves, that they're crazy or something. I know they're probably not, but I can only semantically imagine them existing. It's a bit like imagining a mantis shrimp being able to see light that I can't. I can't imagine what they see, but I imagine them being able to. I imagine an abstract blob of a cartoon character, and I imagine the semantic idea of a future me having drawn something that's identifiably a cartoon character.
Sometimes I hum a melody to myself off of the top of my head. I stick to a scale and I sing notes that might sound good in sequence. I can imagine something semantic like "in two more bars I repeat what I did a minute ago to establish it" but I can't imagine what it sounds like until I sing it. When I pick up a guitar I know semantically that some chords just sound good together, so I think about some music theory and I play it to find out what it sounds like in practice. I don't imagine a final piece that has three key changes and a turnaround that I can hear in my head, I imagine an assignment where I make three key changes and a turnaround mathematically make sense. When I square it off and my math checks out, music theory is pretty much just math, then I get excited to hear what it sounds like.
I still get earworms, they happen. Small snippets of songs can play in my head but it's never the entire song, and I know that it's not quite right sounding. It's a little bit like if Suno generated the refrain of a song and then played it over and over again with half gibberish lyrics. It's only one instrument or vocal at a time, and the rest is super abstract. My earworms almost never go longer than a few seconds long, but sometimes they can go for an entire solo section of a song. If I tried to play any of those songs fully in my head I'd just garble up the song structure. It'd be basically impossible for me to do cryptomnesia stuff with a full song, I'd have to be checking it constantly for reference. Same goes for anything visual, like I can't do much more than abstract representation where I semantically know what it is.
Imagine a brown rectangle, and pointing at that brown rectangle is an arrow that says he's Michael Jordan. Now imagine that brown rectangle not having the arrow anymore, just simply being Michael Jordan. Now imagine it not even being a brown rectangle, just being something that simply is. You're looking at something, in your head, that's Michael Jordan as a platonic primitive. Everything is basically invisible, but I can look around and exist within a space while I'm in my mind palace. Sometimes I can apply color to objects, but it really doesn't matter whether or not I do. It's all just qualia anyways. The idea of "other humans see this and call it purple" is just as valuable as seeing something that's purple in my head. In fact, it might even be better because it expends less energy. It's like being aware of other people's hallucinations without needing to join in.
If you were ever wondering why almost all my drawings are in black and white, that's pretty much why. I don't see the point. Putting in color is more just so that I can accommodate you, like an atheist therapist telling an evangelical gay patient who's in the closet that God has no issues with gay people.