This is the Samsung Galaxy S7 Edge sold in Hong Kong and mainline China. It has a snapdragon CPU and the bootloader can be unlocked (unlike the US snapdragon variant)
This device supports Android 6 and 8 officially.
This device is no longer maintained officially.
There are zero custom ROMs out there although there is a TWRP build: Samsung Galaxy S7 edge (China Qualcomm)
Bootloader unlock: enable OEM unlock in developer settings and use “CROM Service” app (search for it online) to unlock.