By default the Shopify integration syncs products, orders, customers, refunds, and gift cards. Other entities (collections, discounts, locations, fulfillments) sync on demand.
Custom metafields
Settings > Integrations > Shopify > Metafields. Pick which Shopify metafields you want surfaced as Message custom fields. The AI sees them in retrieval if you enable AI Grounding for them.
Multi-store
Connect multiple Shopify stores to one Message workspace. Each store is scoped per agent or per department.