There is an ability to directly access NMEA or UBX data from the TBS GPS.
For NMEA you need to pick any TBS CORE PRO version older than 2.00 and for UBX any version newer than 2.00. The Baudrate for both cases is 57600.
To access the signal you need to cut the +VBATT wire of the BST connector going to the GPS. There is a diode inside the GPS which protects the GPS form +VBATT. The open +VBATT wire of the BST connector, connected to the TBS GPS, will turn into NMEA/UBX data wire. Connected this wire to the serial RX pin of your FC.
It's also important to solder another lead to the GND pin of the BST cable and connect it to GND of the FC.
BST Pinout:
