what you propose is not really possible, because in the admin UI there is no way to display custom fields on a order_line_item basis, so this is not a limitation in the app_system, but rather in the overall custom field system.
However note that you can use the `customField` prop of the order_line_item already to store your apps custom data associated with `order_line_items`.
The custom fields you declare in the manifest are only for the custom fields that should be editable by the merchant in the admin UI for those entities, and there all the entities that currently support custom fields in the admin UI are supported by the app system.
Hello Sebastian,
what you propose is not really possible, because in the admin UI there is no way to display custom fields on a order_line_item basis, so this is not a limitation in the app_system, but rather in the overall custom field system.
However note that you can use the `customField` prop of the order_line_item already to store your apps custom data associated with `order_line_items`.
The custom fields you declare in the manifest are only for the custom fields that should be editable by the merchant in the admin UI for those entities, and there all the entities that currently support custom fields in the admin UI are supported by the app system.