Have you tried thisfinally figured how to install gsi
1 Flash ofox recovery
2 format and multidisabler
3 Unroot, and reboot to download
4 flash twrp
5 reboot to recovery
6 flash patched boot.img, gsi, and kernel
7 reboot to download mode
8 flash stock recovery
9 boot to recovery, and do factory reset
if you trying to flash another gsi, just do from step 3
1. Install Orange Fox
2. Decrypt the data. (Format and run multidisabler)
3. Reboot to recovery.
4. Install TWRP recovery.img into recovery partition.
5. Reboot to recovery.
6. Install GSI