Cardboard cat scratchers work well for rabbits who like cardboard — they are more robust, so they’ll last longer. Something plain like this is fine (My Fable chews them a ton):

For willow toys, it’s great that they’re eating them! You can actually get willow chunks through the Binkybunny Store, which can last much longer, as well as packs of several willow toys (so you have some in stock as they run out!): https://store.binkybunny.com/collections/chews
Getting bundles of sticks/chews can be a good thing to keep them occupied. You can tie them together so it’s something they can destroy, then interact with each separate component.
I recommend the double-weave sea grass mat for digger/chewer buns, as it is more robust then a regular sea grass mat.
I also have posted two DIY toy ideas for more destructive rabbits here: https://www.reddit.com/user/WickandFable/posts/
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.