Obviously Microsoft also advertised for the Galaxy S8, saying that it is the most affordable phone to experience their application on Android, listing it in the device list 'compatible with Microsoft Launcher application' (like Other Android devices are not (!)).
Although Microsoft switched to selling Android phones on both stores, it is understandable, Windows Phone users will consider this as a confirmation that they will no longer develop their own mobile platform.
Microsoft praised the Galaxy S8, saying that the screen is "absolutely awesome" and that you "can trust security" completely. This is also quite surprising when Microsoft also has competitors on its mobile platform. But overall, it is understandable, because they also want to sell.