No fully functional custom ROM exists for retail Passports. The device remains almost exclusively on BB10.
The ecosystem is a testament to hardware longevity. While Apple and Google artificially kill older devices, the Passport survives because of archived autoloaders, dedicated Russian forum members, and the sheer durability of the physical keyboard.
LumiaFirmware.com and the CrackBerry forums host the official autoloaders. Always verify SHA-1 checksums to avoid malware.
Let’s assume your Passport is currently a brick: boot looping, stuck on the red "BlackBerry" logo, or locked at the "Welcome to Setup" screen.
There is a project called "OmniROM for Passport" that surfaced in 2018. A developer managed to boot Android 7.1 (Nougat) on the Snapdragon 801 processor inside the Passport. However, it suffered from fatal flaws: