At the moment, only a limited number of devices on the market have an official version of Android 9 Pie, the last "step" of the green robot published by Google just over two months ago. These versions come from dedicated OEMs that are working with Google.
However, in parallel to this, there is also a whole scene that refers to custom ROMs, made up of volunteers who dedicate their time and their talent for this purpose. As soon as a new version of Android is released, fans of various custom ROMs start asking when they will receive the update.
Of course, they are things that require time and patience, also because the developers who dedicate themselves to this task do it for pure "love for technology". AOSP porting, which is released on various devices as soon as a new version of Android is officially released, lacks many features compared to custom ROMs. However, when it is announced the release of the unofficial porting of a custom ROM as LineageOS 16 for a device, the news can not but please.
This is exactly what happened at the beginning of this week. Thanks to the work of a "Recognized Developer" of the famous XDA forum (which is actually also an official member of the LineageOS team), Xiaomi Mi Note 3 is getting the unofficial version of LineageOS 16.
It should be noted that this version is an experimental build, and therefore we can not expect the (almost) perfection that is instead guaranteed with the official versions. There are many features that already work with this build, and it's a good thing, but at the same time a list of known bugs has already been made : first of all, VoLTE / VoWiFi does not work (and will not be fixed soon), and build has SELinux running in permissive mode.
Recall that Xiaomi Mi Note 3 is a phone powered by a Qualcomm Snapdragon 660 processor, combined with an Adreno 512 GPU, 6 GB of RAM and 128 GB of internal memory.