Depending on your pup's size, treats should be very small and limited. Each piece should be the size of an eraser on a pencil. You can give many pieces throughout the day, but keep in mind that you are feeding a tiny pup. They don't need a tablespoon of anything except at their regular meals.
I give my boys plain Greek yogurt every day after our walks. They are 8 and 9 pounds, and I give them a total of less than a teaspoon. I dip a spoon into the yogurt and let them lick it off. They both have had yogurt from the times they were little pups.
They also get 4-5 smashed baby sweet peas. I use the frozen, no salt added kind.
A lot people use thin carrot slices, apple, sweet potato, green beans, Gerber puffs.
Store-bought treats for dogs are okay too. Stay away from fatty things like Pupperoni. PetSmart and Petco carry healthier treats than what you would typically find at grocery stores, Walmart, or Target.
There are Yorkie Talk vendors who sell home-made treats too. Visit the product sale section to look for those.
Hopefully more people will post what they give their doggies.