Brain games and toys for Boxer

My parents boxer unfortunately had ACL surgery from jumping (if you know boxers you know how much energy they have). She needs to be confined to a kennel with little movement for 12 weeks or she can break her leg. She can only go out for potty and that’s with assistance of a sling. Any recommendations on good toys or brain games I can get them to keep her occupied and not bored in a kennel for 12 weeks? I’m thinking a Kong with treats inside, hidden treat toys. Any recommendations with links would be great.