The Open GApps Project is an open-source effort to bring up-to-date versions of Google application packages to devices that don’t have them. We typically see these recommended after you flash a custom ROM since developers are not allowed to include these applications and services in their custom builds of Android. When a new version of Android comes out, it can take some time before the Open GApps team gets everything ready for the new update. Android Pie was announced just last week , but XDA Senior Member Nezorflame has stepped up and provided the community with a temporary solution.
We are going to be seeing a lot of custom builds of Android Pie released in the coming weeks, so until the official builds of Open GApps are released, we can use these for ARM and ARM64 devices. The developer says these builds are provided “as is” and he cannot guarantee they will work on your device or your custom build of Android Pie. However, they are willing to work on any bugs that may arise during this time of need.