Metafields
Upon installing the Print Panel Shopify app, a read-only metafield is added to your product catalog so your color data is available to any application with product catalog access i.e. Storefront API, Admin API, etc.
The metafield is namespaced under:
app--81604509697--print-panel
Depending on how you decide to sync your data, the metafield is associated to one of the following Shopify models:
ProductProductVariant