Not actually, the FPGA in the VST provides a way to customize its functionality at the Hardware Level. By programming the FPGA chip with the LabVIEW FPGA Module, you could add custom functionality such as control a device under test (DUT) in real time, dynamically control/sequence the vector signal generator (VSG) or vector signal analyzer (VSA), or add real-time signal processing to the instrument.
Refer to the white paper An Introduction to Instrument Driver FPGA Extensions
to see the different ways you can customize VSTs functionality.
In case you need to perform functions such as modulation and demodulation (e.g., BPSK, GFSK, AM, FM), or perform spectral measurements without any custom functionality, you can use NI-RFmx, NI-RFSA, or NI-RFSG.
Refer to the tutorial Choosing the Right Software for NI Vector Signal Transceivers
o better understand the different options for programming a VST.