Install Termux and enable storage access:
Unlocking Android Bootloaders Directly From Termux: A Complete Guide
If you see a serial number, you are connected.
A USB On-The-Go (OTG) adapter or a direct Type-C to Type-C cable to physically link both phones.
If successful, you will see a serial number. If you see < waiting for any device > , your OTG setup is failing (check root permissions or try a different cable).
You can install android-tools (fastboot/adb) in Termux and try:
Lock and unlock the bootloader | Android Open Source Project
Unlocking Android Bootloaders via Termux: Myths, Realities, and Step-by-Step Guide
