Thanks to XDA Developers Senior Member "paphonb," users who don't own one of the few devices receiving the recently revealed Android P Beta can at least try out a new launcher based on that. It's important to note that although the aptly titled Rootless Pixel 2 Launcher will work on Android 7.0 and newer, some features will only work with Oreo. Even then, they aren't guaranteed to show up on all of those devices either. That doesn't make this launcher any less interesting but it's worth bearing in mind before downloading it. With that said, the launcher itself is actually a direct port over from the latest version of Android P.
With regard to the differences between this launcher replacement app and older apps based on Google's stock launcher, there's actually not much to see. That makes some sense since most of Android P's updates are under the hood, primarily centered around A.I. and optimizations. So there's not necessarily a whole lot of changes coming visually to the user side of the equation. Moreover, some of the new features found in Android P are implemented at a system level that can't really be emulated by a launcher, such as the OS's new navigation system. What is there, however, are the new icons, some theming elements such as color changes, dark theming options, and the ability to enable Google Now and weather without installing it separately. There's also Google's new search bar, as shown in the associated app screenshots below, which hasn't technically made it to the official Pixel launcher just yet. That's available as an option in this application.
Obviously, this isn't quite the same thing as having the brand new OS installed before it officially becomes available. That's not likely going to be possible without root access and an increased probability that bugs will be found. Rootless Pixel 2 Launcher is a close second though and will at least provide some of the aesthetics of the up-and-coming Android update. Moreover, it seems as though it may be just about as close as a user can get without serious technical skills or one of the officially supported Android P Beta devices. Best of all, it's free to download via the button below.