Achieving "idle while awaiting external event" behavior of Durable Functions, using DTFx

TL/DR:

Given that Durable Function invocations in an Azure consumption plan [incur no resource costs when idling for external events](https://docs.microsoft.com/en-us/azure/azure-functions/durable/durable-functions-billing#awaiting-and-yielding-in-orchestrator-functions), can other code based on DTFx and hosted in a Functions consumption plan (but not itself implemented using Durable Functions) achieve the same effect?

Details:

I'm implementing a declarative state machine library built on DTFx:

https://github.com/jplane/StateChartsDotNet

...and includes a Functions-based hosting model:

https://github.com/jplane/StateChartsDotNet/tree/main/FunctionHost

In my implementation, state machines can wait for external events. I'm using TaskCompletionSource for that:

https://github.com/jplane/StateChartsDotNet/blob/main/DurableEngine/ExternalMessageQueue.cs

What else (if anything) is needed to achieve the "idle at zero" behavior of Durable Functions in a consumption plan?

Thanks for any pointers or help!