The owners booked it as a house sitting but are having me just do drop ins essentially. Well I came back to drop in on the dog and I guess his owners didn’t put any of his chew toys in his room with him. He had chewed up a Mario kart wheel. I know it’s not a very expensive item but should I buy the owners a new one?
Absolutely not.
If I understand this correctly - the dog was where and how they left him (without toys &with accessibility to a controller etc.), with the understanding you were going to provide visits, not stay at their home. You are in no way responsible to replace damaged objects nor any possible medical related costs.
I’d suggest you might send them an update. When I arrived at approx. time, I noticed that none of his chew toys were in his room. He chose the controller as a substitute. It may need to be replaced in the future. I did/didn’t see any loose pieces. Hopefully he didn’t invest any. Here’s a photo. After I set it aside, we played/went on a walk around neighborhood/cuddled/or whatever. ..