Update 09:40 CST: After further testing, it appears that this trick still results in uploaded photos counting against your Google Drive storage limit. In other words, it doesn't work. However, this trick still works to get the Pixel-Exclusive wallpapers on your phone! The original article is left as below.

One of the greatest and most useful exclusive features of the Google Pixel line, among many, is proper unlimited storage for Google Photos. This feature allows you to back up all your existing pictures and videos in original quality to Google Photos, without having them count up against your existing Google Drive storage. However, this feature is limited to the Pixel, Pixel XL, Pixel 2, Pixel 2 XL, and the Moto X4 Android One edition. If you're rooted, though, there's a small workaround discovered by XDA Member emime12 that will allow you to get Google Photos unlimited storage as well as exclusive wallpaper categories on the Google Wallpapers application on any Android phone running Android Nougat or higher.


Enable Unlimited Google Photos Storage & Pixel Exclusive Wallpapers on Any Android Phone

In case we haven't made it clear before, you're going to need root access in order to continue with the tutorial, so make sure that your phone is properly rooted before continuing. Then, follow these steps:

  1. Download nexus.xml to your phone.
  2. Open your root file manager of choice (we've used Solid Explorer here, but you can use pretty much any root file explorer here such as MiXplorer)
  3. Copy the nexus.xml file you just downloaded and paste it in /system/etc/sysconfig.
  4. Afterwards, set the file permissions to 644 (rw-r--r--).
  5. Reboot your phone.
  6. Once booted up, go to the Settings page for Google Photos and wipe Google Photos' app data. You're done!

Photos will now think that you're using a Pixel, and as such, you should be greeted by a dialog saying that you're now able to use unlimited storage on your Google Pixel device. Also, you should now have access to more wallpaper categories on the Google Wallpapers app, as well as access to the default Pixel 2 wallpaper on the Urbane category.

Optional Build.Prop Edits if Necessary

Just placing the file in the sysconfig directory should be enough for most devices. If, however, placing the above file didn't work for you, you will have to get your hands even dirtier. Download BuildProp Editor and then find and change/set the following build.prop values:

        ro.product.model=Pixel 2 XL
    
        ro.product.brand=Google
    
        ro.product.manufacturer=Google
    
        ro.opa.eligible_device=true
    

Update 1 - Magisk Module

Here's a Magisk Module by XDA Senior Member dariomrk in case you want to make these changes systemlessly (and thus pass SafetyNet).

Update 2 - Further Testing

Redditor /u/stek29 has performed some more testing of this trick and has discovered that you may not need to wipe data in Google Photos, the file need not be named nexus.xml, and that the only flag being checked for is apparently NEXUS_PRELOAD.

Update 3 - Uploads May Still Count Against Drive Storage

We're hearing reports that this trick was discovered by the team over at OpenGapps a few months back and was quietly patched by Google already. In that case, applying this trick will still result in uploaded photos to apply against your Google Drive storage (ie. it doesn't work). We haven't confirmed this ourselves, but if/when we do we will update the above tutorial.

Update 4 - Google Photos Unlimited Storage Not Working, Pixel Wallpapers Still Work

I have confirmed that photos uploaded in "original quality" using this trick still count against your Drive storage. My Drive shows that I uploaded 0.2GBs of photos and videos from yesterday. This means that the trick was patched, likely when it was discovered by the people over at OpenGapps. It's strange that this trick somehow still triggers Google Photos into showing you the original quality onboarding message, though.


Explanation

Instead of the usual (and easily copyable on other devices) approach of a simple build.prop flag, eligibility for some Pixel-exclusive services and features (like unlimited Google Photos storage) is defined in the nexus.xml file, included by default in all Google Pixel phones in the system/etc/sysconfig directory. The system partition is readable without root, meaning that all apps can easily check for a value in said system partition. And some Google apps, like Google Photos and Google Wallpapers, check for specific flags in the nexus.xml file in order to provide specific features to Pixel users. However, as long as your phone has this particular file, these apps will believe that the user is using a Google Pixel, and will, therefore, enable these exclusive features on your phone. So simply inserting it to the system partition using root access and a root file manager will do the trick.

So far, we have tested this on a Moto G 2015 running an unofficial Android 8.0 Oreo ROM, and we can confirm that it works. However, it's sure to work on most Android Nougat devices. And while we cannot guarantee that it works on Marshmallow or lower, it's possible since the app only seems to be checking for specific flags in the nexus.xml file instead of system-related values.

It's highly possible Google will patch this in the short term - after all, it's not the first time we find shortcuts we aren't supposed to find. So, we encourage you to test this out and give us feedback in the comment section. And be sure to check the original tutorial, originally made for the Xiaomi Redmi Note 3, if this worked for you!