i recently managed to flash gsi using fastboot instruction:
fastboot flash system system-quack-arm-aonly-vanilla.img
from https://github.com/phhusson/treble_experimentations/releases/tag/v213
they don't have twrp for my device so i had to use fastboot.
i wanted to know
how do i flash the gapps img. file (or how can i get gapps?)
and how do i fix ussd and phone calling function which does not work?
everything else works perfectly