The CyanogenMod based official Lineage OS builds will be going live on the official website this weekend in one of the biggest ever launch release for an Android custom ROM. The official Lineage OS builds will be available for both Android 6.0 Marshmallow and Android 7.1.1 Nougat platforms via the official download portal.
Every week there will be a new release candidate build, following the rollout of the official builds. Unlike the unofficial builds of Lineage OS which are already available for download, the official builds will receive regular bug fixes and feature updates from the grassroots-project-development team.
According to the developer blog post, the official builds of Lineage OS will not include ROOT functionality. However, the users will be able to install root on their device through a separate downloadable zip file.
In addition, the developer team has promised to offer experimental builds for data migration from CyanogenMod to newer Lineage OS ROMs. Prospective users can install the migration build before installing the official Lineage OS ROMs and thereby transfer all their user data from previous CM installation.
It is imperative to download matching versions of Lineage OS on your device as migration of CM13 ROM (Marshmallow based) to Lineage OS 14.1 (Nougat based) will not work due to compatibility issues between Marshmallow and Nougat based firmware. Instead you may migrate or upgrade from CM14 ROM to Lineage OS 14.1 as they will have the same base firmware.
After installing the migration build, you can easily upgrade to the latest weekly official builds of Lineage OS without losing data.