What's a book, though? I suppose people would at least count a traditional e-book. Does long-form fanfic count? How about a book-length website? What about one that was originally published as a book and then republished online?
I think it's obvious enough without getting into the weeds like this unless their sample size is unreasonably small. E-book yes obviously counts. For the rest, like fanfic? Probably, but does it matter here? Is this actually going to move the needle?
All your examples could be printed and read as books - whatever form they are consumed in. What differences are you seeking to highlight with these examples?
I'm sure the general population being asked whether they read books have a very clear idea of what a book is.