Did you find the solution to your case? We are having a similar case where we want to specify increment quantity for each product and use it in the store front end?
Topic summary
Liquid’s quantity_rule object exposes min, max, and increment for variant quantities, prompting questions about where these values are stored. Initial checks showed no corresponding fields in the standard ProductVariant Admin GraphQL API and no obvious entries in catalogs.
Recent update: The feature is tied to Shopify’s B2B functionality (per a Shopify changelog on personalized B2B buying with quantity rules and customer-specific publishing). It appears in Shopify’s free themes (e.g., main-product.liquid) where the quantity_rule is referenced in the UI.
Open questions raised: Whether it relates to the new cart/checkout validation API (no supporting docs found). Attempts to locate data in catalogs initially failed.
Outcome: Clarified that quantity_rule is available only on B2B commerce stores, with official documentation provided (Shopify Help: B2B theme code for quantity/pricing). The thread acknowledges this limitation; for non-B2B stores, the feature isn’t available. Resolution reached; no further action items noted.