Hello,
there is a Spectrum Analyzer program available for the ADALM Pluto free of charge called SATSAGEN. It has a signal generator as well. The program will perform the frequency and bandwidth extension of the hardware so you can use it from 70 MHz to 6000 MHz. Should be sufficient to challenge the Siglent SDS 2000X Plus
You can find it here:
http://www.albfer.com/en/2020/02/21/satsagen-2/Kind Regards
jse