I don’t have aphantasia, but I do think in an audible stream of words.
This has led to an odd quirk in my experience as a software developer: I hate keywords or variable names that don’t have an obvious pronunciation, like “fn”. They interrupt the stream and make me stumble in a way that doesn’t seem to afflict people who appear to experience written words as grouped glyphs without hearing them.
(I’ve chosen to read “fn” as “effin” as a puerile expression of resentment.)