With lab-grade spectrum analyzers, working up to > 1 GHz, many of them work down to 9 kHz (I don't know where that exact frequency comes from).
For example, Siglent SSA3000X Spectrum Analyzers offer a frequency range of 9 KHz to 2.1 or 3.2 GHz.
My ancient Marconi 2380/2382 RF spectrum analyzer goes from 100 Hz to 400 MHz.
A very useful thing lacking from the Tiny SA series, at their extremely low price, is a tracking generator, since the generator function cannot be used at the same time as the SA function.