A wheel is a great addition for hedgehogs. Be sure to buy a giant sized wheel that is 11” or so in diameter. It should also be made of solid plastic, so the hedgehog’s feet won’t get caught while running.
Other toys could be toilet paper rolls, cat balls with bells, toy trucks to push around, plastic PVC pipe fittings, tunnels… the list goes on. Be creative, but make sure the hedgehog can’t get caught in it.