Although older, this open-source app was a pioneer in unlocking the Samsung Galaxy S III directly via the Android operating system. How to Use GitHub Tools for Unlocking
For older devices like Blackberry, Huawei, and ZTE, this Go-based program calculates the official network unlock codes required to free a device from its original carrier. sim unlock github
Always perform a factory reset and remove the SIM card before attempting a software-based bypass. Although older, this open-source app was a pioneer