Unlike Qualcomm phones, MediaTek devices like the F3 do not use fastboot oem unlock . Instead, you must use or a patched lk.bin file. Search XDA for “Opposite F3 bootloader unlock without data loss.”
The Oppo F3 (CPH1609) did not receive an official Android 7.0 Nougat update and remains supported only up to Android 6.0 Marshmallow. While unofficial custom ROMs may be explored, the device's MediaTek chipset offers limited options compared to the F3 Plus. For discussions on third-party firmware, visit the Oppo - XDA Forums .
If you search “Opposite F3 Nougat update” on Google, you will find fake news blogs and YouTube clickbait. The is different. Here, real developers and enthusiasts post verified files.
XDA Developers forums were active around the Oppo F3 Nougat update, highlighting several recurring themes: