Of course the firmware is only Qualcomm if the modem is Qualcomm. QPST/QXDM allows you to mess with the modems by sending it commands and changing configs yeah

Of course the firmware is only Qualcomm if the modem is Qualcomm. QPST/QXDM allows you to mess with the modems by sending it commands and changing configs yeah. But if you want to flash the firmware that's something else. Yeah the firmware integrity mechanism are not the best, and there's definitely vulnerabilities in the firmware. But there's still no way of installing unsigned firmware on more recent devices, and I've never come across a way of running unsigned code without it being really obvious. There was a bug recently that allowed you edit baseband memory from within the OS, but again you'll never be able to hide that from Qualcomm on a million devices.