Agree with the others. There's a lot of rubbish out there about mixing foods. Usually people do it to try and achieve the right level of protein. But Hazel Hamster has everything in that's needed - all nutrients and enough protein - and it's sugar free - even hamsters who aren't prone to diabetes can still get tooth decay and toothache!
Hazel Hamster is the same as Harry Hamster - exactly the same formula. Hazel Hamster says 16% protein and Harry Hamster says 18% protein but they are exactly the same formula. The Us labelling requirements and workings out are just different from those in the Uk.
So Hazel Hamster on its own is absolutely fine. Adding some freeze dried chicken for extra protein every other day or so won't do any harm either and will also be fine.
I wouldn't use the tropical mix at all - dried fruits can be full of nasty preservatives.
For treats and extras things like pumpkin seeds, peanuts in shells (more protein) are good.
For extras I give a very small piece of veg each day, half a nut (either a plain cashew or half a brazil nut or half a walnut) and the odd pumpkin seed scattered every couple of days.
You'd be better going to the supermarket bakery counter and buying some small bags of plain walnuts and brazil nuts and pumpkin seeds
The thing they enjoy most is the bit of daily veg! Every 3 days to start with then after a week every other day then after another week, every day, so their stomachs adjust.
Broccoli, carrot, cucumber, baby corn etc are all fine. For an extra special treat occasionally some fresh fruit is better than the dried fruit. But not citrus. So a blueberry or a bit of strawberry or apple or banana.