tinySA

The tinySA is a small spectrum analyzer or signal generator, primarily intended for 0.1MHz to 350MHz input/output but it has some nice other capabilities:

Spectrum Analyzer with two inputs, high quality MF/HF/VHF input for 0.1MHZ-350MHz, lesser quality UHF input for 240MHz-960MHz or
Signal Generator with two output, sinus output for 0.1MHz - 350MHz and square wave output for 240MHz-960MHz when not used as Spectrum Analyzer.
Switchable resolution bandpass filters for both ranges between 2.6kHz and 640kHz
Color display showing 290 scan points covering up to the full low or high frequency range.
Input Step attenuator from 0dB to 31dB for the MF/HF/VHF input.
A built-in calibration signal generator that is used for automatic self test and low input calibration.
Connected to a PC via USB it becomes a PC controlled Spectrum Analyzer or Signal Generator
Rechargeable battery allowing a minimum of at least 2 hours portable use
Max input level +10dBm. Do not destroy your tinySA
Due to the low cost and very small form factor there are certain relevant limitations.

Project website:https://tinysa.org/

Wiki & User group:https://groups.io/g/tinysa/