I consider myself aphantasic and would describe my process similarly. I can kind of "draw" shapes in my head with sort of strokes of light like a kid writing their name in the air with a sparkler. While doing it, I can in fact feel my eyes physically moving around under their lids. Anything that isn't a rudimentary shape is out. This comes in handy while thinking about software because I can pretty easily create and trace connections between things in a sort of imaginary network.

I experience basically the same thing with sounds, which I've never heard anyone talk about. If you ask me to imagine the guitar solo from "sweet child of mine", I'm not going to hear the actual song in my head, I'm going to hear essentially the same thing as if you asked me to describe it (with lots of beedly dee type sounds). I can recognize a person's voice, but I can't will it into existence without hearing it, instead I would hear my own imitation of them, however bad that is. I'm not sure if that's a common experience but media tells me it's not.