Applications, but surely not drivers? The Linux QMI SDK depends on GobiNet and GobiSerial.
I would have used whatever serial driver exists in FreeBSD, made sure it could bind to the QDL function on “boot and hold” mode, switched to this mode using the AT!BOOTHOLD command, and then used the simplest possible uploader code to push the file to the modem.
Building this on FreeBSD should not require too many changes: swi-update.c\utils - libqmi - QMI modem protocol helper library (mirrored from https://gitlab.freedesktop.org/mobile-broadband/libqmi)
Note that this code is very hackish, and is not really used by libqmi anywhere. It’s just in the repo for historical reasons. But the code is simple, and should work with a little hand holding from someone knowing FreeBSD.