LineageOS is available for the Samsung Galaxy Mega 6.3 and 5.8 and this gives you latest Android 7 Nougat for the three old phone. LineageOS is based on AOSP project. Everything is working except for the second SIM card slot. Also, screenshot feature is not working and recent app thumbnails are coming out to be blank.
Everything is working including Wi-Fi, Bluetooth, RIL (Calls, SMS, Mobile Data), Sensors (Accelerometer, Compass, Light, Proximity, etc.), Camera, Video (playback & recording), Audio (playback & recording) and GPS.
* Install a custom recovery with SELinux support or latest CWM Galaxy Mega recovery.
* Download the latest build.
* Wipe data/factory reset if coming from stock or another ROM (You may get a “staus 7” error if you fail to wipe.)
* Flash the ROM and then GApps and reboot your phone
It is an amazing firmware for those who are looking for bloatware free experince on their android phone. It also has support for f2fs and to enable that, you just have to download the modified TWRP recovery from here and flash it. Make sure not to flash a kernel that does not support F2FS. In case, you want to go back to ext4 format, you will have to format the data and cache with Galaxy Mega’s TWRP recovery to ext4 format.