Google now has two launcher apps in the Play Store, but you probably can't install the new one. The Pixel Launcher is one of the selling points of the Pixel phones, and remains technically exclusive to them. But of course, we have the APK available for download.
Having the Pixel Launcher in the Play Store means several things. First, Google can push updates to the launcher very easily. If you want to sideload the launcher, the versions published on the store will be mirrored quickly. That's better than waiting on APKs from system dumps to show up. Additionally, it would be very easy for Google to flip a switch and make the Pixel Launcher available for more phones. We don't know when or of that will actually happen, though.
There do not appear to be any change in the features of this version. Everything listed in the changelog is a feature Google already demoed. If you want to sideload the Pixel Launcher, we've got the new version on APK Mirror .
PS: Did you see Google's subtle rickroll?