An interesting measurement would be to show the limitations of components. For example, very few electrolytic capacitors are useful above 100 kHz. Resistors have parasitic inductances and capacitances that limit their use to low frequency in many cases. You can measure a wire wound resistor to determine its characteristics at high audio frequencies.
If you purchase carefully, you can get a nanoVNA that goes as low as 10 kHz.
Apart from finding limitations of components, it is useful for ordinary measurements. Just testing L, C, and R at low frequency can be handy.
For what these cost, they are unmatched in usefulness.