Via Odin you can't change a Chinese SM-S9110 to a US phone. You can change it to a Hong Kong or Taiwan phone. Hong Kong has Google Play preinstalled. Careful if you do try flashing the USA XAA variant to a Chinese phone, the phone will get stuck in a soft brick. None of the recovery methods online worked (emergency recovery etc.), I had to unlock the bootloader from the download menu, then it would boot again. I relocked it but the damage is done. Goodbye Samsung apps that rely on Knox security, they will never come back. Note I was able to flash Hong Kong firmware with the bootloader locked, which would have been ideal had I known that ahead of time.