I’m converting a bedroom with hardwood floors to a rental room and am adding a small food bar with refrigerator, microwave, etc. What would be best to place under the food bar over the hardwood floor to protect the floor but yet would not allow moisture to accumulate underneath it and affect the floor?
Thank you!

Most rugs and mats are fine to lay on the hardwood - what traps moisture is that rubber sheet you sometimes get with the rug to help keep it from sliding. All rugs and mats will affect oxidization, so you can expect some color variation over time between the exposed wood (which will get lighter) and the covered wood (which shouldn't change much at all).