avluis

It's newer...

Will more than likely get released whenever Pioneer feels like getting off their buts... or if you pay them...

I have it -- no issues so far~

I would join this community and ask for answers there -- something is different with the Pixel (XL) that will more than likely need a workaround:

https://productforums.google.com/forum/#!forum/android-auto

A few things to cover in order for us to be on the same page:
 

I take it you have the Pioneer app already installed on your Android phone.

You have launched this app, logged in and done whatever you needed to do in order to get your account re-linked to Pioneer.

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On the stereo, you have switched from CarPlay to Android Auto mode (I believe there is an additional mode that will disable Android Auto as well, try that).

In the navigation app, remove the currently paired device (the iPhone 6) -- this is somewhere in the settings for the navigation software, not the settings for the radio itself.

While setting this up, disable Android Auto auto-launch until you are done setting this up.

Personally, I do not use Pioneer's offering -- the offered apps are not 'good' enough for the road and for me Android Auto (and even CarPlay for this matter) offer all that I need.

I don't know your needs so I cannot speak for you -- but from my usage of the 8100 NEX both in CarPlay and Android Auto, AVIC Sync was just not good enough to bother with nor pay for.

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Let me know if you need me to try something on my stereo as I have an 8100 as well (as mentioned) along with a Nexus 6P (USB Type-C as well).

On another note -- what is the firmware you currently have installed on your 8100?

I've got into the habit of pressing mute on my steering wheel as I disconnect my phone and turn off the car~

Took a while to get used to this but it works.