It looks like Samsung has begun testing the Galaxy S9 in earnest. Galaxy Club is reporting that both the regular S9 and the Plus models are currently being tested with Android 8.0.0 Oreo. There's nothing concrete to go on here, but it should come as no surprise that Samsung is putting its upcoming flagship through the paces already. Software development takes time, and testing usually starts early to make sure the software and hardware work well together in the final product.
Galaxy S9 software testing underway with Android 8.0.0 Oreo
Galaxy Club notes that the Galaxy S9 is being tested on Android 8.0.0 and not Android 8.1, but that's yet another unsurprising factor here. Samsung has never been the leader when it comes to launching new phones with the most current Android build, and Android 8.1 is in the beta stage for even Google's Nexus and Pixel devices. Then there's also the fact that not every point Android version upgrade has features that are targeted at non-Google devices.
Furthermore, Samsung often has some of those features already implemented in its software before Google brings them to the core Android OS. Samsung could switch to Android 8.1 at a later stage in the testing process, but going by the way the company usually handles things, it might not happen until a few months after the Galaxy S9 has gone on sale. The same goes for the Galaxy S8, which is most likely going to get Android 8.0.0 when the Oreo beta program ends and the official update begins to roll out.
