The Lineage OS team released first nightly build of LineageOS 14.1 for Google Pixel C tablet. Of course, Pixel C is one of the assured devices that gets latest Android OS update, but if you would like to experience custom ROM on it, then the official LineageOS 14.1 build (based on Android 7.1.2) would be the best choice. Yes, Pixel C is eligible for Android 8.0.0 upgrade, so even if you installed LineageOS, you can easily revert the device back to stock (an advantage of Google devices) to get the update in time.
In the below guide we show you how to install official LineageOS 14.1 custom ROM on Pixel C tablet. If you are new to Lineage OS, this is one of the most popular custom ROMs and the latest version (LineageOS 14.1) is based on the Android 7.1.2 Nougat. The custom ROM brings several new features, lot of customizations and latest security patches (June 1, 2017) to Pixel C.
As you may know, installing LineageOS 14.1 requires unlocked bootloader, latest version of TWRP recovery and root access on Pixel C. Also, note that the status of LineageOS 14.1 is nightly, which means it is unstable and may include bugs.
Disclaimer: Follow the instruction at your own risk. We will not be liable if any damage occurs to your device and/or its components. It is recommended for technically talented users only
2. Boot your Pixel C into TWRP recovery (switch off the device, press and hold Power & Volume Down key and choose Recovery mode)
3. In recovery, select ‘Backup’ and create a backup of your device (recommended)
4. Now, select ‘Wipe’ and then ‘Advanced Wipe’. Select Cache, System and Data partitions to be wiped and then Swipe to Wipe.
Once installation has finished, return to the main menu, select Reboot, and then System. The first boot will take several minutes. (Source)