Flashing your device and carries a risk of "bricking" (making the phone unusable). If you encounter a "Just a second" boot loop after flashing, you may need specific fix files to bypass the setup screen.
, or at least a way to flash system images via Fastboot. This brings us right back to the main issue. Furthermore, even if you could unlock the bootloader, GSIs are not perfect. They often have bugs, particularly regarding hardware support (like the camera, VoLTE, and fingerprint sensor) because they lack the specific vendor drivers for the device. vivo y1s custom rom