I wonder if the whole premise and all conclusions you reached in this thread are corrupted by your lack of understanding of basic input and output protocols listed in specifications? I suspect all of them, given there is almost no similarity between the 2 devices; they are not in any way equivalent.
USB gadget mode is a legit thing, but all things considered, for just a standard 2 channel i2s, I dont know why you would hack a zero to be a USB->i2s, when it would need so many supporting circuits just to make it equivalent to a simple $40-50 device