Not only did Sony Mobile confirm that various phones will get Android Pie from November (more details below), but it offered an interesting insight into the development process behind rolling out a non-vanilla Android update. 

Before we get onto that though, Android Pie will roll out to the Xperia XZ2XZ2 PremiumXZ2 CompactXperia XZ PremiumXZ1 and XZ1 Compact from November while the XA2XA2 Ultra and XA2 Plus will get Android Pie in "early 2019".

Sony also published the below infographic that gives an insight into how Android updates for third-party devices are developed after getting the software from Google "a few weeks before a new version of Android is released". Sony then says it needs to get the software to work with all its chips (because it uses different components that Android Pie was developed on).

Subsequently, the software goes through "Sony-fication" - yes Sony calls it that itself. Basically, they're all the Sony-specific additions like modifications to the camera app. Then there are a lot of real-world tests and lab tests to carry out before the software can be revealed to the public plus operator tests and custom versions, making sure everything connects OK and finally, gaging customer reaction after its released. 

It's a long process, is basically what Sony saying. And that's why you don't get Android Pie on third-party devices from day one. It takes time. "We always aim for the quickest possible upgrade rollout from the time Google makes its announcement to when it reaches your smartphone" says Sony. "It’s essential that Sony engineers have the time to implement all our feature upgrades and test devices to meet our high-quality standards."

Don't forget to check out our guides to Android Pie: Android 9 Pie features and details

Here's Sony's Android software development process in a nice infographic with mountains and a waterfall: 

Sony MobileSony explains why Android version updates take so long image 2