That is right, there is no device control capability with just wiring for analog audio.
I suggested the cheap solution because it is a technically functioning solution, like with the info buttons. I don't believe in paying close to $100 for a OEM branded audio jack unless it does something no other component can do.
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I answered the question by stating that USB will not be possible without changing the head unit, then kinda strayed off that and suggested a normal 3.5mm female jack with plug insertion detection.
From what I read, the problem is that the vehicle once had a working AUX port as they all do, but the mechanical connection is having issues.
I'm not sure where the iPod-specific thing was brought up or why it is relevant to this.

Any analog audio source will work with the auxiliary input.