to my knowledge, the wontons aren't available anywhere else in the park. and believe me, I love them so much that I would make it my knowledge! Yak and Yeti is run by an outside company so I don't think you would find their items outside of the restaurant.
that being said, I've had them twice and they are kind of my favorite thing in the world. the first time, I went with my family/was on the dining plan, otherwise I might not have had them because I don't usually order dessert.
the second time, I was on a solo trip and totally craving them. I walked into Yak and Yeti around 2 pm on my day at AK, with no ADR, sat down with no wait, ordered the wontons, and was out of there in probably half an hour (and I even took my time.) so if you really wanna try them but don't wanna order an entire table service meal/don't have the dining plan, see if you can get a walk-up. Or even just book an ADR to only order dessert, no reason you can't. A walk-up probably won't happen at a busy time, I was there in early October and crowds were low to moderate.
I will say that the wontons are 100% worth it. they are one of my all-time favorite desserts. I've made them with decent success at home but it's just not quite the same. good luck!
