qspectrumanalyzer VS gqrx

No. QSpectrumAnalyzer has some feature overlap and can use HackRF with hackrf_sweep or soapy_power.

Here is some good news though: There is a way work around this sampling rate restriction. Since you don't really care about the actual data, and you're more trying to just visualize the traffic, there is a special mode that HackRF's support called "sweep mode." In sweep mode, the HackRF will rapidly re-tune the antenna across a huge swath of the spectrum to give you a birds-eye-view of a much larger frequency range. Unfortunately, CubicSDR (and most other SDR software) does not support the HackRF sweep mode natively, so you'll need to use another tool, such as "qspectrumanalyzer" which supports this view. Qspectrumanalyzer is a python application that can interface with a HackRF and work in sweep mode, giving you a view 1 MHz - 6 GHz almost once per second. Granted, you'll want to tweak this down to just the 2.4 GHz range and play with the setting to get the view just right, but it should be possible to see what you're trying to see.

qspectrumanalyzer (https://github.com/xmikos/qspectrumanalyzer) will do this.

QSpectrumAnalyzer is an example of a tool that can make use of this.

There's an issue open for this: https://github.com/gqrx-sdr/gqrx/issues/1104

I could really use some help from a software build expert. Gqrx and all its dependencies would need to be built in CI with Apple silicon support, and I don't know how to do that.

If you don't need the web interface and your usual desktop SDR software supports rtl-sdr tcp mode, you can easily set up a small board that calls rtl-sdr with the appropriate parameters so that it will wait for a remote connection from the above software, not unlike what happens with WebSDR, but you would be using your usual desktop SDR application which would be native and much more snappy than a web browser. Here's an example using gqrx.

https://www.youtube.com/watch?v=74jDcHuDCmE

https://gqrx.dk/

GQRX works pretty well for me. There is also CubicSDR and SDRAngel afaik - you might just want to play around with them and see which you are most comfortable with.

SSB/CW (also (W/N)FM/AM/Raw) using GQRX

For most signals (including analog AM and FM modes) you can use a laptop with an RTL-SDR USB dongle (fairly cheap), or another SDR, and a reasonably tuned antenna. Various RTL-SDR models can tune from around 500 kHz up to 1.75 GHz with 3 mhz of bandwdith, and works with free software like SDR# for Windows and GQRX for Linux. It works with lots of other software, too, for ham modes, digital modes, etc.

Some of the Crossfire modules have a rudimentary spectrum analyzer function on them that might help you identify if there are other devices operating in the 900MHz band around that area, but I'm not sure the nano TX is one of them. I have a couple RTL-SDR dongles or equivalent I'd use with GQRX as a cheap spectrum analyzer if possible.

Good old GQRX for me https://gqrx.dk/

There is loads of software that will work such as SDR++, GQRX, CubicSDR, and SDRangel just to name a few. For HD radio reception, there is nrsc5. Nrsc5 only works with an rtl-sdr, so you will need one if you want to receive HD radio.