Ok some further reading later....

The MC7750 is a CDMA only card and it appears DIP does not support CDMA hence the MC7750 cannot work in DIP mode.
I vaguely remember knowing that at one time previously but I seemed to have forgotten. 🙄

It appears you may be out if luck here. There is no support for QMI mode in FreeBSD/pfSense.

I suggest looking at a different card. 😞

Steve