I applaud your initiative to write a story about Palestine.
I could tell you my own experience, but I wouldn’t dare to guess what Palestinian kids dream nowadays — life was much simpler and easier when I was a child there in the 1970s and 80s. There was no wall, no aerial bombing, etc.
My most persistent dream was to fly, to be a pilot and go places. The joke is that Palestine was not free and had no airline, so that was an impossible dream. Later during the First Intifada, when soldiers confronted us every day on our streets and at our schools, my most persistent dream became a free Palestine, imagining ways to get there, ways to resist.
If I may suggest, take a look at children’s drawings from Gaza. The drawings give you a good idea of the dreams, or nightmares. You can find online galleries of such drawings with the right search.