This is a great day to make a resolution to build a homebrew radio for the shack. You have lots of options and choices.
That said having personally built many radios it is best to start small. KK4DAS is launching an extended buildathon in January, over Zoom, to construct a 40 Meter Direct Conversion Receiver. That is an appropriate place to start small.
Once you have successfully built the DCR then you can think about an SDR. KK4DAS also has a homebrew SDR project just over the horizon so you want to join Dean at the hip.
Currently I'm about 20% through the book Ghosts of Honolulu by Mark Harmon and Leon Carroll Jr. It is striking how much intelligence gathering was taking place in the Hawaiian Islands as early as 1936.
The hero of the book is a birthright US citizen of Japanese ancestry who is recruited to work in the ONI (Office of Naval Intelligence). His work was key to winning the war. Also, of note, the concept of a SCIF was employed to evaluate and read highly classified information only they called it a "black room". (SCIF = Special Compartmental Information Facility).
It is also clear that internment camps were being planned as early as the late 1930's.
Fast forward to today and in question is the team that is about to take over our government in three short weeks. Do they have the experience, skills and savvy on par with those who had those jobs in 1940? But we're stuck with the players selected. Wait until they find out they actually have to do work.
Happy New Year!
73's
Pete N6QW