A wellness check up is always a good idea when bringing a new bunny home.
First of all, it’s great that you were able to take him in and are so active to become informed on what you bunny needs. If you would read the diet section here because it is full of valuable information for the best diet for your new bunny. He should in no way be eating hamster food. He’s a rabbit, not a hamster. They have different dietary needs and therefore different food. Rabbit food shouldn’t have any seeds, nuts, or fruit bits in it, just plain pellets. Oxbow is a respected brand but there are many others that fit the bill as well. Bunnies must must must have access to hay at all times. It’s really important for their digestion and it keeps their teeth trim. I would make it my first priority to get him eating hay. Timothy hay is the standard for adult rabbits but any type of grass hay (not alfalfa) is okay.
Fruit should only be a treat since it’s high in sugar but many leafy green veggies should be staples in a bunnies diet as well. The diet section has a list of bunny safe veggies. It’s important to only introduce one new veggie at a time and slowly so that he can adjust to the new diet.
My suggestion would be to get him on hay and then slowly transition him to good pellets. After that start introducing veggies. Just take things slow and gradually change his diet. Sudden changes can cause an upset so slow and gradual is the key.