Not much is understood about this release, include whether the Alpha was intended for distribution through the Google App beta channel. However, Android Police is reporting that some users have been able to access Google Assistant on their non-Pixel phones after installing the the v6.13 alpha release. This could mean that Google Assistant will be rolled out more widely to Android phones once v6.13 goes to general availability or it may be just for testing. Either way, some users were excited to get access. Let us know on the Google Home | Assistant LinkedIn Group if you install the Alpha and are able to activate Google Assistant.