Android 8.0, currently codenamed 'O,' has only been available for approximately a week as a developer preview, but XDA Developers have already been hard at work extracting and creating a method for users on Android 6.0.1 and up to give Google's new Pixel Launcher a try. The launcher was placed on the site on March 24th. However, there are a few warnings provided by XDA contributor linuxct, that users who want to install the app should be aware of. As such, it may be best for non-developers - or those with less technical knowledge - to wait for a more official release or at least until any major bugs have been squashed.
First, the contributor who posted the method and appropriate files mentions that he signed the APK with his own unique key, so if you have a previous version of the launcher, you'll need to uninstall that first. The first time the application is launched, it will also generate a new file called "reflection.engine." linuxct says that file is required by the launcher applications and since the file won't have previously existed, the launcher will force close while the file is created. Users will need to wait around a minute before relaunching the Pixel Launcher. Of course, if it still doesn't launch properly, users should create and submit a system log so that the problem can be rectified in the future. The launcher will also generate a "Google Now" page on the left panel of the home screens if the app is set as a "system app."
There are probably other bugs that will need to be worked out as well, as indicated by the 'testing' flag applied on the listing itself. That is to be expected since this is effectively just a "backported" version of the application, pulled directly from the developer preview itself. By default, it is technically intended to run alongside the official developer preview for the upcoming OS update and to be mostly handled by developers. It bears repeating, as always, that some caution is required with advanced installations like this one. That said, if you're feeling particularly adventurous, instructions to install the latest Pixel Launcher from the Android 8.0 preview can be found via the source link below.