Even some republicans call the USA a democracy. It is as if they have never read the constitution.
I don’t think people are confusing a federal republic and the unitary state when they call America a democracy, they are just plain wrong, America is nowhere near being a democracy and neither are most of the other so-called democracies whether they are federal republics, unitary states or constitutional monarchies, or run by Putin for that matter. Maybe Hungary is a democracy (if you define a democracy as a place where the majority of citizens get to run the place the way they see fit).