Have you taken a look at this? https://microsoft.github.io/coyote/ https://microsoft.github.io/coyote/learn/overview/what-is-co...
It's a tool by Microsoft Research to detect concurrency bugs in code.
That said, there's also https://github.com/Azure/azure-functions-durable-extension which seems closely related to Orleans, but for serverless.
Durable Functions are great for deterministic synchronization across calls to other Azure Functions. Fan-out, fan-in, function chaining, and similar tasks are best done using Durable Functions[0].
Could you build an actor model on top of Durable Functions? Possibly. I'm not sure why you would do that, though. Azure Functions are already pretty expensive.
[0]: https://docs.microsoft.com/en-us/azure/azure-functions/durab...
https://docs.microsoft.com/en-us/azure/azure-functions/durab...