Unlike Samsung or Pixel phones where "ROM" often refers to a custom OS like LineageOS, a BlackBerry Passport (often called an "Autoloader") is a signed, low-level firmware package. These files are usually in .exe or .signed format.
Despite the end of support, the BlackBerry Passport remains a beloved device among some enthusiasts, who continue to experiment with custom ROMs and modifications to keep the device alive. blackberry passport rom