If you detonate a nuclear weapon above a city, no matter how far above, you will call upon you a nuclear response. There’s no difference between an EMP attempt and a nuclear strike. So why would you attempt an EMP attack when that means giving up most of the destructive force to maybe burn out powerlines, and guaranteed surface nuclear response on your territory?
Stuxnet like attacks are way way more plausible and likely.
Like HS physics
It comes across as somewhat condescending and naive to refer to a HS class as having a notable amount of science background. And a reason to dismiss other sources of information.
Or, the HS physics overview that you and I share simply doesn't dip very deeply into these topics.
If I recall correctly they mostly used RDX.
What does actually work and have been operationally used are graphite bombs designed to short out electrical equipment. Those are much cheaper and more effective than EMP weapons.
I don't think you can say EMP weapons don't exist. I know what you're trying to say, but attacking a city with an EMP strike will be seen international ly as far more favorable than an actual strike.
Also, an EMP strike can be detonated really high in the atmosphere where we would have zero chance to intercept and is more economical for non first world countries.