In my experience, having an "approved" something to chew is VITAL in preventing chewing on "UN-approved" somethings -
Even hay is included in that and the one time I ran out of hay for a couple days (BAAAAAAD human!), the boys just went nuts and chewed to death things they never touch otherwise - my couch cover, my notebooks, the carpet ...
my buns have never gone for the toys or grass mats I've bought over the years -
they prefer the cardboard boxes said toys come in
they really like working on shredding the old phonebook too -
they've also enjoyed apple branches to gnaw on if you know someone with an apple tree ---
Some bunnydecided to work on destroying the mat in front of the bathtub so I replaced it with an old cotton towel and let them have at it - (we're on the 2nd one now) -
when Mopsy decided he couldn't stop digging at the carpet in the corner, I put a couple of old phonebooks there and he decided he liked them better -
good luck! it just takes a bit of experimentation