Does this not directly, nakedly violate the sovereignty clause?

Pretty much this. The US will now end up with an automotive ecosystem (including fun things like ambulances, firetrucks, buses, etc) where everything is built as cheaply and dangerously as possibly profitable (see: Pinto et al). Sure, the autos we build here aren’t going to be able to be sold anywhere with a functioning regulatory body, but that’s OK because we managed to save $20 on each car we build by not having to include pesky things like airbags or a steering column that won’t impale you in a crash or a body that won’t telescope into you and crush you.

Not “obscure”, but nobody has noticed that their fixer in my cyber-magi-punk modern-day Faerun game, Mr B, who has magical abilities that should not be possible with conventional magic, who has a ton of canaries in his office, and whose guard/retinue at the bar he owns all dress in the same outfit with the same gold shirts, *might be something more than just a guy.

They’re currently trying to stop Tiamat’s resurrection, but nobody has asked “hey, is our fixer literally Bahamut?”.