And I don't think anything sold in the US today, not to the Department of Defense, has anything that poses "an immediate and extreme health and safety hazard".

Smoke detectors contain highly toxic Americum 241 isotope. It's not that hard to remove it from the ionization chamber.

Most modern domestic smoke detectors are now photoelectric, rather than ionization based.

Not only do they not contain toxic Americum 241, photoelectric smoke detectors are also both more sensitive to real fires and less prone to false alarms.

(The later is actually really important, as people will often disable smoke detectors in response to a false alarm - and then forget about them)

We had a kitchen smoke detector in college that was kept swaddled in plastic wrap at all times because it went off every. time. we tried to cook something. Absolutely a safety hazard, yeah.

…while it remains sealed in a layer of gold. It's not easy to get the Americium out.

I'm mostly thinking of high-voltage capacitors. Basically, if sticking a screwdriver in the wrong place could maim or kill you, I'm okay with having security screws there. Otherwise, no.

I’d say cars to belong to that category. Oh, and guns sold to private citizens maybe?

I don't know, an electric car seems like it would contain a few items you don't want to be poking at if you don't know what you're doing. Security screws could a pretty good job of keeping the casual DIYer from electrocuting himself, essentially a "can't open this? Maybe you shouldn't."

Microwaves have high voltage capacitors the size of your hand, which you should absolutely discharge during maintenance.

Airbag assemblies/controllers tend to have these.

Particularly in the era of self driving cars, wouldn't vehicle parts qualify for that?