Orchestration Trigger via FastAPI

#### Is your question related to a specific version? If so, please specify:
V2 Model

#### What binding does your question apply to, if any? (e.g. Blob Trigger, Event Hub Binding, etc)
Azure Durable Functions Orchestration Triggers

#### Question
We're planning to write several API endpoints using Azure Durable Functions. We'd like to use FastAPI and its several features like OpenAPI, JSON Schema validation. We cannot use non-Durable functions, because we have potentially long-running tasks such as approval flows, or tasks may intermittently fail and have to be retried until completed.

I've found an article how to use FastAPI with an HTTP Trigger, but you can't just use that information and do the same with the Orchestration Trigger.

The conceptual flow or the orchestration is this:

1. Client sends JSON to Orchestration Trigger HTTP endpoint to start the orchestration e.g., to request the creation of an object in a cloud-application.
2. The JSON describes what activies the orchestrator calls, in which order and what parameters is passes.
3. If the JSON body is invalid, the orchestration trigger should return an error message and not start the orchestration at all.

And also, we want to provide a generated OpenAPI/Swagger documentation for the orchestration triggers.

Is this even possible at the moment?