I found a sample test with 133 questions. I got 126 of them for 94.74%.
There were a few history questions that threw me, specifically related to the federalist papers of which I’ve got scant little memory.
I felt like the rest of it was pretty straightforward. I also think recent divisiveness has made a lot of the questions related to how the federal government is structured a lot easier.
As to your assertion that most natural Americans would fail, I’d flip a coin on that. Maybe? Probably?