Yes there is a contraption for such purposes.
A Book Display Stand
The come in many sizes and variations. They have little arms that can be positioned to hold open the pages.
On some units you can adjust them for different sizes of books and it eliminate having to deal with problematic reflections created by glass or plastic.
I wouldn't rule out putting a glass sheet on top, but don't just dump it on the book - using spacers under the glass so the pages only touch at one point (technically a line) and adjusting the glass height and possibly angle should allow pages to curve and get you most of the way towards the effect I think you're looking for.
An alternative might be ...