Demian, I think this is a great idea. I believe one of the strongest motivators for the feasibility of something like this is the effectiveness of marketing for packaged foods, such as snacks, cereals, etc!
There were some mentions of great advertisements collaboration in the comments, but It's hard to find anything like this today, at least in Canada.
It would be very interesting to see the effects of targeting children in healthy foods, and I like your idea of actually designing the shopping experience around the audience as opposed to simply the branding.
I like this idea! Specifically, I think it does a very good job of addressing a core issue when it comes to healthy eating, which is developing a tendency to try new foods. And we know that kids do have quite a different palette than adults, and that they might not adapt to different foods initially, but developing a habit of being comfortable trying new foods might allow a palette to develop more quickly over time.