The proper US diet is Higgins Vita Garden - not Sunburst which is loaded with dried fruit which really isn't appropriate for hamsters, and the Mazuri isn't that high quality either.
Mineral chews aren't really good for hamsters in the first place. Their nutritional needs are to be met with their diet and these are really just unhealthy junk food that can cause serious dietary imbalances anyways so it's a great thing your hamster isn't chewing the one you have!
I know we can get Applaws cat or dog foods in the US(wet, not dry) which may be worth trying to tempt your hamster into eating more. Pure Bites also have some non dry options like this:
PureBites Chicken Pate Cat Treats, 2.5 oz. | Petco
Unfortunately not every hamster likes millet. If you haven't tried flax seed already, that would be a good idea for extra healthy fats. You might have to mix either(or both to see if it works with millet just in case) with a safe baby food for example to disguise the taste and see if that helps.