Recently I swapped out my CX-5’s head unit for android auto, and ever since then I’m trying to find a clean way of reusing the USB port inside armrest. That has turned into a loooong journey…
Depending on the trim/options, the connection options get *quite* complex IMO. I can only speak for my setup, and hopefully that helps others.
My car is a Grand Touring with Bose, and without “Tech package” which iirc includes HID headlight, GPS, city braking, and maybe homelink. I opened up my trims (took a while figuring out which panel is which and where all the clips are), and I found both the bluetooth module and the siriusXM module installed. Both are installed behind the glove box, so you don’t need to take off any panel/trim to access it, as glove box can simply be popped off.
The USB port in the center armrest is connected to the bluetooth module, and the connector going into bluetooth module looks like this:

Took me a lot of googling, and I can only find the model for the receptacle: It’s JAE MX39 connectors. Those are specialized USB2.0 connectors from Japan, and apparently they are not for retail sale – JAE seems to be building the harness in-house before selling the whole harness to mazda.
That pretty much stopped my project right there. I was hoping that I can find the proper connector to build myself a cable, rather than hacking up a USB cable like someone did here , now if I want to put a USB port in armrest I’d have to swap out the whole USB/AUX assembly… but wait…
The inner wall of the armrest has a hole in the front, enough to pass through a USB cable, and my headunit actually has a fairly long cord that ends in a USB port, so all I really had to do is to run that port as close to armrest as possible, and get a long enough USB cable, feed it through the hole, and i’m good. Sure it’s not a reuse, and doesn’t look quite clean inside the armrest, but hey, now I get wired Android Auto.