You can now migrate an existing Project using the InMigration value of productCatalogModel in public beta. This lets you migrate an existing Project from the Classic to the Modular catalog model in stages, instead of in a single cutover, giving you more control and flexibility over the migration process.

In the InMigration state, resources that reference a Variant resolve from modular Variants, while products and product-projections continue to return embedded Variant data and Variant update actions on the Product API are still accepted. This lets you migrate your reads and writes on different schedules. You can also use the x-catalog-model request header to resolve a single request against a specific catalog model, so you can validate your integration before changing any Project configuration.

For steps on how to migrate an existing Project, see Migrate to Modular Catalog.