FEASIBLE

A gamified experience (a website, app...) that teaches people of all ages the basics of farming. I don't know anything about seeds, moon cycles, tools... No matter the progress, at the bottom of the "Society stack" there are still simple techniques that the average man is not aware of.

UNFEASIBLE

Worldwide Sushi on demand. It's not feasible, but I would love to just order sushi with an app and receive it at my doorstep, like pizza.

That said, It would be a nightmare to scale. You would need to educate the consumer on the quality of your fish and fight the bias "home delivery --> cheap".