GApps packages (short for Google Apps) are essential in the custom ROM development community. The reason why GApps are not bundled with custom ROMs such as LineageOS is that while LineageOS is an open-source Android distribution, Google apps are not open-source. Apps such as the Play Store, Gmail, Maps, etc, do not use the Apache or GPLv2 license. Therefore, custom ROM developers can’t bundle them with their builds, as doing so presents legal challenges.
Throughout the years, many different GApps packages have been popular. ParanoidAndroid GApps used to be one of the most widely used GApps out there, but the packages were discontinued in 2015. In the same year, Open GApps sought to carry forward where ParanoidAndroid GApps had left off.
The distinguishing feature of Open GApps is that it has been completely developed by writing build scripts that allow for the automated creation of new updated packages automatically, according to the developers. Their development process is open-source, and builds are generated every (European) night.
Since its first release, Open GApps has gradually went on to become the most recommended GApps package out there. It allows users to choose from ARM, ARM64, and x86 platforms, with supported Android software versions ranging from Android 4.4 KitKat to Android Oreo.
The recent release of LineageOS 15.1 has increased user interest in custom ROMs. Recent developments in Project Treble have also meant that the development community has something to look forward to, after years of seeing an era of increasingly locked-down devices which has stifled development. The first builds of LineageOS 15.1 were released this week (based on Android 8.1 Oreo), but OpenGApps did not offer GApps for Android 8.1 Oreo (specifically, the SetupWizard was still 8.0).
This changes now as OpenGApps now offers packages for Android 8.1 Oreo for the ARM and ARM64 platforms. Android 8.1 packages for x86 and x86_64 aren’t supported yet, but this should not affect most users, as very few Android devices are based on either of these two platforms.
OpenGApps warns that GApps packages for Android Oreo are still “beta quality”. However, the release of GApps for Android 8.1 Oreo means that they are now compatible with Android 8.1 custom ROMs such as LineageOS 15.1. As such, users no longer have to use alternative GApps packages which aren’t automatically updated. They can flash the Open GApps packages via TWRP — and it should be noted that the GApps packages must be flashed immediately after flashing a custom ROM (before rebooting to system) in order to avoid crashes.