: Official TWRP support is currently unavailable for this model. You may find "unofficial" or ported builds on community platforms like 4PDA , but these carry high risk of bricking your device. The Unlocking Hurdle
Currently, there are no official builds from major ROM projects (LineageOS, Evolution X, etc.) for the Y1S. GSI Compatibility: Since the device launched with Android 10, it supports Project Treble vivo y1s custom rom
Without an unlocked bootloader, you cannot flash a custom recovery (like TWRP), let alone a custom ROM (LineageOS, Pixel Experience, etc.). For the Y1S, the bootloader is a digital Fort Knox. : Official TWRP support is currently unavailable for