The Google fields can be updated with Stock Sync by using the metafields.


Google FieldsMetafield namespace and key
Google Product Categorymm-google-shopping.google_product_category
Gendermm-google-shopping.gender
Brand
mm-google-shopping.brand
MPNmm-google-shopping.mpn
Size
mm-google-shopping.size
Colormm-google-shopping.color
Custom Productmm-google-shopping.custom_product




To know more about metafield click here.