Important: You'll need to replace YOUR_METAOBJECT_DEFINITION_ID
with the actual ID of the "Press reviews" metaobject definition from the target store. After you create the metaobject definition using the first mutation I provided, you'll get back an ID that you can use here in the validation value.
This metafield allows you to attach a list of press review metaobjects to your products, making it accessible from both the admin and your storefront.
Or, you can look up the ID with this GraphQL query:
query GetPressReviewsMetaobjectDefinitionId {
metaobjectDefinitionByType(type: "press_reviews") {
id