The Switch's screenshot feature is going to be getting a workout.
http://www.nintendoworldreport.com/news/57279/game-builder-garage-will-only-support-sharing-with-codes-at-launch
Codes will be the only method for sharing Game Builder Garage creations at launch.
IGN confirmed in a preview that there would be no other methods supported for viewing other's games aside from the codes.
"In my hands-off preview of the game, the Nintendo representative on the call told me that aside from sharing codes with others manually, there would be no organic discoverability features in the game. No 100 Mario Challenge, and no built-in browser to find new or popular games." - Rebekah Valentine, IGN
The Nintendo representative explained that the game was aimed at pre-teen and young players, with a focus on sharing within a family or close friend group who would "know what they're downloading".