Metafield $app namespace

Is there a way to register the $app as a namespace on app owned Shopify metafield? I see that there was a previous thread regarding this subject here : https://discord.com/channels/836317518595096598/1395644957024583861 The custom workspace works fine. However writing $app or leaving the field blank do not seem to be supported Shopify documentation for reserved namespaces in metafields : https://shopify.dev/docs/apps/build/custom-data/ownership#create-metafield-definitions-with-reserved-namespaces Thanks!