Latest Nova Launcher 6.0 beta brings some nifty new features
The most important new feature mentioned in the changelog is the option to launch the Google Assistant straight from the search widget on the homescreen. This option can be disabled from the toggle you'll find in the Nova Settings.
Apparently, the new feature doesn't really use the same method employed by the Pixel launcher to trigger Google Assistant, but it's the closest that the developer could include. More importantly, the new feature doesn't require the Prime version of Nova Launcher, so it will be available to everyone.
Another change included in the update is a new set of Nova app animations that draw inspiration from Android Pie. Also, some fixes are mentioned in the changelog as well, so you should notice fewer issues with Nova Launcher 6.0 beta 5.