When I run out of dog food my go-to is raw eggs/bananas because they're always in the house. Those are also my Pug's favorite food/treats. If I train her to do something new, or she's showing good discipline, I'll reward her with either. She has raw eggs every couple months and bananas as treats a couple times a month max. Is this hurting her?
Eggs are quite high in fat and not generally recommended to be given frequently. But using them for training purposes only is a great idea. Just remember this rule of thumb: Whatever human food you are giving your Pug, imagine the food amount being 3-4 times bigger and that is what you would be feeding to a human. Ever so often with bananas is OK. Once a week is all good and adult dogs can handle a little variety with small amounts of treats/human food ever now and again. Never feed the following though:
-Seeds and nuts of any kind -Grapes -Raisins -Onion -Garlic -Chocolate (you'd be surprise how many people think a little is OK)
With the rewarding good "discipline", I'd try to move away from food if it's a general sitting when asked, unless you are teaching a new behaviour, than high rates of rewards to begin with and then fading to a verbal command and then to a hand gesture, coupled with the verbal command