Is there any app that extend the SKU/Product to allow work with the GS1 Smart Search Standard?
Not that I’m aware. But do you need this?
I just tested a product page from a test store I use to build our documentation with a tool I found on the implementation guide you shared. Results seem pretty thorough, which tells me that compatibility with this standard might be something we have out of the box.
By the way, all apps that are available to all stores can be found either in the VTEX App Store or, in some circumstances, in the 
vtex-apps Github organization.
Yes, it’s something that will bring better results using context information to the Search Engines (Google, Bing, Yahoo …)
The main objective is too markup information specific to a type of product following the GS1 Smart Search Standard, like for example a Food Product.
The implementation you have out of the box follows the Google Standard for the Schema.org and has the basic information a product or SKU can have.
The GS1 Smart Search extends this feature to allow markup information to more specific type of Products like:
-
Consumable Products (Foods, Drinks, Tobacco Products)
→ Allergen Details
→ Diet Type - Example GluttenFree, LowFatDiet, LowLactoseDiet, …
I didn’t find any app at VTEX App Store or vtex-apps
Another link that gives a well context about this feature:
1 Like