activities for a dog in isolation

I am hoping for some ideas and suggestions for a dog I'm fostering.

He's currently in isolation in our above ground "basement", but it's a smaller space. He spends the majority of the time sleeping, as he should, and I do spend time with him. I am just worried in less than a week as he's recovering, he's going to get incredibly bored and will not be sleeping as much. Any ideas for toys or other items that will keep him engaged for when he's feeling better?