^That's why I do website annotations, and sometimes appendices: Those are places to put all the research and worldbuilding that don't go into the story itself.
Not a bad idea.
I certainly understand the impulse to squeeze it all into the actual book. You put all that work into your world-building and/or research, so you don't want it to go to waste.
But here's the thing: All that effort does
pay off, even if the reader can't see it, because it allows you to write about your imaginary planet (or 16th century Hungary) with confidence and consistency.