Usually they do this sort of thing professionally and they use these skills in their hobby projects as well. An electrical engineering degree would be a good start to acquire these kind of skills, alternatively a hardcore HAM or very serious hardware hobby.
FPGA stuff isn't hard to pick up at all. At least to do basic stuff.
(I got as far as building my own HDMI-outputting simple video chip with a character generator, tied to a RISC-V processor, addressing SRAM, booting a primitive OS. But I kinda fizzled out after that when I ran into SD card interfacing)
