is extremely difficult because the device has a that has never been officially or unofficially fully bypassed for retail units . BlackBerry’s security architecture uses a hardware-verified "Root of Trust" that checks for official digital signatures before the OS will boot.
There are extremely rare "engineering" or prototype units that shipped with unlocked bootloaders. Some developers have successfully ported LineageOS 18.1 (based on Android 11) to these specific devices. Hardware-Level "Restomodding" Blackberry Priv In 2024... Is it still usable? Blackberry Priv Custom Rom