The Android 5.0 Lollipop was releases about two months ago and it has hence been available for Google Nexus devices and Play Edition devices only. On the unofficial side of the coin, many other devices are already running on the Android 5.0 Lollipop.
Now, the OnePlus One too can already update to the latest OS. Unfortunately, the Android 5.0 Lollipop ROM developed for the OnePlus One is in its Alpha build which means that it is not stable yet.
Nevertheless, installing the Android 5.0 Lollipop built for the OnePlus One will grant the device with an OS that is almost identical to that on the Google Nexus 6. The differences are with the OnePlus One, getting an added ability to have either onscreen or physical navigation buttons.
The Android 5.0 Lollipop is available for the OnePlus One and users can acquire it at XDA’s forum. There, users will also find an installation guide that will tutor them on every detail about the Android 5.0 Lollipop ROM.