Google Allo updated with a pair of Android 7 Nougat features
To launch Allo in split screen mode, open the app and hold the recent apps button on your device – it's shaped like a square on Nougat devices like the Google Pixel or the Nexus handsets. You can then open any other app you want to use while keeping Allo active and on top.
As for inline replies, simply pull down on the notification shade when you receive a notification from Allo, and tap Reply. The keyboard will show up and you are ready ti start typing.
Allo can be downloaded from the Google Play Store here. It doesn't require Android Nougat to function, although the new features it received in the latest update are indeed limited to the new platform.