For my pointer I use a cheap bamboo chopstick, I have found that my gcc does not really like millet, so I will usually use a strawberry(well, any type of sweet fruit.) or sunflower/safflower seeds.
Another Idea for a treat would be peanuts, although these are really not a healthy treat (+they have to be roasted because they are known to carry harmful fungi.), my conure is too small (or lazy) to break through these, and if you were to use them it will probaby take a while for your sun conure to eat.
Good luck