It's a huge amount of work. It looks like at least a PhD's worth. Huge achievement for a hobbyist.
Again not diminishing the work but adjusting the expectations, this output is not from a curious guy in a shed. He is a trained Electrical Engineer working as a Senior Consultant/Scientist in RF design for a Finnish Engineering Consultancy.
This guy clearly has a breadth and depth of knowledge from his professional career which he brings with him into his out-of-office projects.
What's impressive is that he did the RF part, the SAR data reduction part, and the drone control part. Those are different skill sets.