I think you're right to be skeptical. Probably a good portion of it is just psyop and propaganda. If you look at the footage from the 50/60's it looks fake. The claimed size of the explosions just gets more and more fantastical and everything is hyped. It smells (and looks) like the US-Russian space race.
The biggest nuke ever to be detonated, tsar Bomba, was said not intended to be used in war. They supposedly created it just to prove how big and bad they were. Well, why not simply make some great footage and lie about the whole thing? The ivy Mike footage is just goofy. And the damn thing wasn't even a bomb, it was a house.