It's supposed to be a way to unlock the bootloader on international devices I think.. Someone can correct me if I'm wrong since I don't know a whole lot about it because I'm in the USA and have use for it.. I'll attach it for you to look at and see if it's something you can use.
it doesnt work on usa models...
i researched this apk back when it popped up on S6 days and again for S8/S8+...
Since some might not know Ill post info on it now so ppl that search will hopefully see it as im sure itll come up multiple times haha
So HK/China typically have Snapdragon variants similar to USA models. However there are a few differences with the main difference being the BOOTLOADER:
1) HK/China variants BL has something called a CROM Lock (thus you get a CROM service apk)
2) USA variants DO NOT have a CROM Lock in the BL
3) The apk needs ONE lib file we do not have for it to function: libkwb.so (short for lib KIWIBIRD)
4) The CROM service apk will run on USA devices so long as the libs pushed accordingly.
5) The apk simply writes a "KIWIBIRD" flag to the /dev/block/steady partition.
6) On HK/China variants, since their BL has a CROM Lock, checks for this flag. When it sees it, it essentially turns the CROM Lock off which, for them, means unlocking the bootloader.
7) Since USA variants DO NOT have a "CROM Lock", our BL completely IGNORES this kiwibird flag. Thus rendering it useless for USA variants.
To add:
*NO, you CANNOT flash a HK/China variant BL. In ODIN/COMSEY ODIN it will FAIL to flash. If you force it after root by DD, YOU WILL HARD BRICK. This has been tried on S8/S8+ by two people and both resulted in a HARD BRICK which means stuck in EDL mode