Service Bus Output Bindings for Topics & Using Custom Properties

When sending messages via output binding for Service Bus Messages to Topics, the output parameter is of type "func.Out[str]" and only supports .set(val:str) and does not presently support setting ServiceBusMessage custom properties that would be useful when utilizing Topic Subscription filters, in particular.

Is there any plan to expand the output binding variables to support more than just string for Service Bus Messages? Sequence number, custom enqueuing time, other operations supported by the separate azure-service-bus Python library's ServiceBusMessage class?