I mean if a standard engineer that maybe saw a taste of low end military was actually presented with a circuit, would we go 'holy crap that belongs in the art of electronics as its own chapter' or would it be more like 'they dotted their i's and crossed their t's'?
The early weapons were barely electronic at all. The Los Alamos "gadget" (tested at Trinity site, and basically just put in a housing for dropping on Nagasaki (called "Fat Man") used a vibrator and rectifiers to to generate several thousand Volts to fire a spark gap that triggered the exploding wire initiators for the explosive lenses. A capacitor dumped through the spark gap to a signal distributor that ran the firing pulse to the initiators through matched-length coax cables. REALLY simple stuff.
The only electronics in Fat Man (and I'm guessing in Little Boy, also) were the altitude trigger, which was based on aircraft radar altimeters.
You can clearly see the radar altimeter's antenna on pictures of Fat Man.
Don't worry about a visit from the feds, this is REALLY old technology, and pretty well documented in many places.
Modern weapons have gotten a lot more sophisticated, using 2-point initiation and a neutron gun based on a linear accelerator, instead of a tiny neutron source at the center of the Plutonium. So, there has to be some precise timing so the neutrons get to the center of the Plutonium "pit" right at the moment of maximum implosion. I've never seen any mention of how they do this.
Instead of a spark gap, they use a gas device called a Krytron, also a pretty highly classified device. They were in the news some decades ago as Iran, I think, was trying to buy some. The pulse discharge capacitors are also classified, I think Saddam Hussain was trying to buy those, or get details of construction.
Finally, there are systems to prevent unauthorized use of these weapons, called Permissive Action Links. These are REALLY restricted, as they want to make sure the guys trusted with handling the weapons do not know how to defeat them. If the PAL is tampered with, it will fire the initiators in the wrong sequence, blowing the weapon to dust. These are supposedly a mixture of electronic and mechanical parts. DoE was at one time looking into using MEMS to make it harder to figure out how the PAL works or defeat it. I don't know if that got implemented.
Jon