No, SFCC gives the inventory data as part of the products.
Algolia uses `queryAllSiteProductsSorted()` from the SFCC API to get all products. Then we compare each product with the ones previously indexed (that we keep in a snapshot): When we have 2 products with the same id, we compare their fields, and if some have changed, we send those updated fields to Algolia. The record is updated using partialUpdateObject: Partial Update Objects API Reference | Algolia
Note: If the number of fields in the product differs from the snapshot, we reindex the product entirely.