It is not currently possible to determine whether a field is added onto a specific screen or get any details on its properties via the API. This would be very useful for more complex integrations such as chatbots where the screen model could be built into the chatbot by querying specific screens such as the portal submission screen for its added fields and their associated properties (e.g. label, mandatory requirement).

It could also be useful for dashboards to be able to easily see the schema of used fields vs. standard un-used and system fields