What's AOSP?
AOSP is Android as Google publish without other modifications. More or less AOSP is the Nexus devices stock rom without gapps.
We added few non-AOSP features for a better user experience and we NOT going to add something other.

What's working :
Boots
RIL (Calls, SMS, Data)
Fingerprint
Wi-Fi
Bluetooth
Camera
Camcorder
Video Playback
Audio
Sensors
Flash
LED
GPS

Known issues:
Tap2wake (fixed)
In Call Proximity Sensor doesn't work (fixed)
Audio output while playing/selecting ringtones
Audio output on Wired Headset doesn't work
Permissive for now.


Instructions :
Download build
Reboot to recovery
Flash RealmeUI C07/c09 OZIP
Flash the AOSP build
Flash NiKGApps
Format Data
Reboot