Google is reportedly testing a piece of software on the HTC Nexus 9 tablet called "Andromeda," which is rumored to be the merged Android/Chrome OS software that had been talked about initially in rumors last year. While there is no confirmation from Google on this particular software just yet, a report today seems to display that the software is indeed being tested on this device. This is also following a report from not too long ago (which initially surfaced yesterday) that Google's merge Chrome OS and Android software could end up being teased at their upcoming event on October 4th, and that the software was called Andromeda internally at Google.
Andromeda being tested on the Nexus 9 begun as a rumor, but it seems that the AOSP for Android 7.0 Nougat reveals some code that mentions graphics performance testing while referencing Andromeda for the Nexus 9 and talking about its performance score. This doesn't actually mean that Google has plans to release Andromeda for the Nexus 9 in any capacity, rather it is likely just the device they have chosen to test the software on. It's also worth considering that a merged version of Android and Chrome OS software (in this case, Andromeda, as it now seems to be known) wouldn't likely be ready for release until sometime next year, and by the time Google could have a build ready for a public launch, the Nexus 9 will be well past two years old.
Even if Google doesn't have plans to launch Andromeda for the Nexus 9 though, the fact that they're seemingly testing the software on a tablet could mean that they have plans to release the software for future tablets, and may have needed to gather an absolute minimum in terms of hardware requirements. That said, there is still a lot that isn't even known about Andromeda in the first place. Google has not officially announced the software or the project of working on it in any official capacity, so there is no real way to know what direction they plan to take it. More details look to be not too far off in the future though, if Google does in fact plan to discuss Andromeda in some way at their October 4th event.