Since the NanoVNA covers from 10kHz up, one can use the sound system of a PC with suitable software to provide the lower frequency coverage. Even the most basic sound chip in a PC will cover 20Hz to 20kHz, and often the low frequency coverage extends to a few Hz. Some better audio cards also offer coverage beyond the audio range, to 40kHz or even more.
Software like ARTA-LIMP allows making useful measurements.
Smith charts, I don't know. I don't use them much myself, as for most situations I find standard X/Y charts more practical. But of course it's perfectly feasible to write VNA software for the PC sound system, that generates Smith charts too.
