Can't get Prism 8 with DryIoc RegisterServices and Platform-Specific support to work

[horizondave]

EDIT: I've created an example repro using a "Prism Blank" template from VS2019 https://github.com/horizondave/PrismBlank

Trying to use Prism 8, ContainerLocator, IHttpClientFactory and Platform-Specific Service registration with DryIoc Extensions (not Magician) in a Xamarin Forms application. To be clear, this used to work fine with Prism 7.2 but I would really like to use the features of 8 - specifically scoped services !

I have these nuget packages installed

Prism.DryIoc.Extensions
Prism.Forms
My main Xamarin Application inherits from PrismApplicationBase.

In platform code (eg Android) I have IPlatformInitializer implented by MainActivity and for platform-specific services I use:

LoadApplication(new App(this));
as documented here: https://prismlibrary.com/docs/dependency-injection/platform-specific-services.html

This line causes the IContainerExtension to be resolved in the shared code

protected override IContainerExtension CreateContainerExtension()
...but I can't find a way to successfully return a valid IContainerExtension implementation.

I've attempted:

https://prismlibrary.com/docs/dependency-injection/container-locator.html

var createContainerExtension = () => new DryIocContainerExtension(); ContainerLocator.SetContainerExtension(createContainerExtension);
But the code given here can't even compile - the DryIocContainerExtension class created is defined INTERNAL and isn't available to my application code.

If I use...

PrismContainerExtension.Init();
or
return ContainerLocator.Current;
or
return PrismContainerExtension.Current;
...as worked previously (eg Prism 7.2) I get a runtime error as described here: https://githubmemory.com/repo/dansiegel/Prism.Container.Extensions/issues/180

ValueFactory attempted to access the Value property of this instance.

Please can someone advise what I'm doing wrong?