Install Android 9 Pie for Nexus 5X with AOSP ROM port

The software support for Nexus series has been officially dropped. This includes the last Nexus 5X and Nexus 6P series devices as well. The Nexus 5X is nearly 3 years old now and it has got its fair share with Android 8.1 Oreo. Although Google may have abandoned these devices, they are still some stunning smartphones. A lot of people possess it as their primary or secondary phones. So the development community is still active for these devices. Hence, we are getting the first ever Android 9 Pie ROM for Nexus.

Yes, the Nexus 5X (bullhead) can now be updated to Android 9 Pie with the unofficial AOSP ROM port. However, for this, your device need to be rooted with latest TWRP recovery installed. Also, the two devices do not come with Project Treble support officially or unofficially, you will need a special Kernel for it to run.

Thanks to developer argraur (check source), we have this stunning AOSP 9 Pie ROM for the Nexus 5X. However, do note that it is the first build and may come with some bugs. Currently functioning things are:

Boot
Power
Fingerprint
RIL (unstable) (with Google Apps)

How to Update Nexus 5X to Android 9.0 Pie with AOSP ROM port?

Make sure your Nexus 5X is rooted with latest TWRP recovery installed. How to install custom TWRP recovery?
Download the Android 9 AOSP ROM from here. Also, download the SphinX Kernel from here and Google Apps (gapps) for Android P from here.
Transfer all the files from above to device or phone storage.
Reboot into TWRP recovery.
Take a full Nandroid Backup of system, vendor, boot, data partitions.
Got to TWRP home and Wipe data, system.
Flash the AOSP 9 Pie ROM by going to install.
Similarly, Flash Sphinx kernel (necessary).
Also, flash the Google Apps package.
Reboot to System.