We all have different anecdotes. My two flemmish babies have no interest in chewing their plastic litter boxes ....they have four through the house. The boxes are full of oat hay. They eat a lot of this. I've also bought some chew toys, which they are not too interested in. My wife and I have several cardboard boxes under the dining room table. They love to crawl into the boxes and jump in them and chew them. I've been lead to believe that they can eat cardboard without harm...it is cellulose for the most part. We have mostly hardwood floors, but we have some carpet tiles down, since the rabbits don't like smooth floors. Some of the carpet tiles had plastic fibers that they wanted to chew, so we got rid of them. I think they can safely chew cotton and wool from the carpet tiles (in small amounts). Our previous rabbit was an adult when we got her. She was chewy, but not as bad as our now babies. They did want to chew our wood furniture....which is bad because its varnish coated. I bought some 2x4 pieces of untreated pine timber and sat them down in the house and they've done a good job chewing the 2x4's. (For metric people, a 2X4 is wood that is 1 7/8 inches by 3 7/8 inches ...2.54 cm per inch).
Remember, cellulose..in vegetables, paper, cotton, is a polysaccaride. Bacteria in bunney's stomach changes cellulose into glucose. The glucose keeps the bacteria alive, and the extra glucose keeps the bunny alive.