Unlike Xiaomi or OnePlus, Vivo does not officially provide bootloader unlock tools for the 1801. Historically, developers used exploits (like the QFIL test point method or MTK Bypass) to unlock the bootloader on the Snapdragon 626 variant.
For a budget device from 2018/2019, the Snapdragon 439 is a capable but entry-level processor. As apps have become heavier and Android versions have advanced to 11, 12, and beyond, the hardware struggles to keep up with the manufacturer's heavy software skin (Funtouch OS). This hardware limitation is the primary reason users seek custom ROMs—specifically lightweight ones like LineageOS or Pixel Experience—to reduce lag and extend battery life. vivo 1801 custom rom
If you manage to flash a GSI or a ported ROM, you gain features that the stock Funtouch OS lacks: Unlike Xiaomi or OnePlus, Vivo does not officially
The Vivo 1801 has a 16MP sensor (Sony IMX376). Stock ROM uses proprietary Vivo camera blobs. Custom ROMs often use generic Snapdragon cameras. As apps have become heavier and Android versions