Hi! You can give your hamster Whimzees - they’re edible chews for dogs but safe for hamsters. I’d say about one a month is okay, and a lot of hamsters tend to like them! You can buy them on Amazon.
You could also try leaving a chew toy or two in his food mix for a few hours and then give it to him; he might chew on it just because it smells like his food. If not, you can mix flour (preferably buckwheat flour, it’s the lowest in fat...? I forgot lol but it’s the best option) and water in order to create a glue like paste, and then brush this paste onto Apple wood sticks (or other chews) and then attach some of his seed mix onto the paste.
Mine doesn't chew on anything either that's why I bought them. They are totally safe for hamsters and they are made for dogs and cleaning teeth so it'll help wear the hamsters teeth down really well. But don't leave it in the tank because its too much food overall. Leave it in there for like a couple hours then take it out. Or even a one night a week depending on how much she chews. Mine chews it like once a night for like 10 or so minutes so I just leave it in the tank all the time but if your hamster goes a little overboard then just limit her ability.
If your hamster limits herself and you can leave it in the tank all the time, then I still recommend removing it from the tank every so often so she doesn't get bored with it and stops chewing it.
Here's the link on amazon: https://www.amazon.com/dp/B01F71E5Z2/ref=cm_sw_r_cp_apa_i_oGD.EbZ4KNT7V
They are also sold at Petco and I believe petsmart as well. I know Petco has them, the one near me has them on like a stand near the check out but if you buy the bag it's cheaper per alligator. Either way they're easy to find and cheap.