Where is the demo project?

I would like to compare what I'm doing (wrongly, it seems) to the video. Where's the demo project?

In short, I'm seeing that the runtime is complaining with

[SwiftUI] Publishing changes from background threads is not allowed; make sure to publish values from the main thread (via operators like receive(on:)) on model updates.

despite using @MainActor.

And, it isn't clear where to instantiate the model object. I get a warning

Expression requiring global actor 'MainActor' cannot appear in default-value expression of property '_manager'; this is an error in Swift 6

So while this is very promising, it is hard to discover the correct and modern way to implement asynchronous behavior in SwiftUI.