I was using Avalonia, but the syntax is pretty much the same.
I found samples.AvaloniaApp hard to apply, as I was so use to the Winui + MS DI way of doing things.

Looking over it again, Log TT is an injected service and Clock.Models.Timer is an implementation of ClockViewModel's required ITimer interface. I'll try again in the morning and get back to you.

I managed to put together a ViewLocator source generator* for another multipage app, but had little luck injecting non-view services, so I'm trying to use Pure.DI.

Thank you for your answer.

Yes you are right the approach to Avalonia is the same. If we want to do MVVM:

• In the App.axam file, register the resource:

<Application.Resources>
 <local:Composition x:Key="Composition" />
<Application.Resources>

• And then use it everywhere at the view level - bind the desired view model using data context, for example in the MainWindow.axaml file:

<Window xmlns="https://github.com/avaloniaui"
 ...
 x:DataType="avaloniaApp:Composition"
 DataContext="{StaticResource Composition}"
 ...>
 <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" DataContext="{Binding ClockViewModel}">
 <TextBlock Text="{Binding Date}" FontSize="64" HorizontalAlignment="Center" />
 <TextBlock Text="{Binding Time}" FontSize="128" HorizontalAlignment="Center" />
 </StackPanel>
</Window>

• When customizing the composition, you need to remember to define the roots of the preposition models as:

.Root<IClockViewModel>("ClockViewModel")

because unlike classical DI container libraries, to optimize code generation, their number should be as small as possible and therefore each root should be defined explicitly. It is better to have only one at all. But in the example 2 are created for the sake of example.

Feel free to ask. If you create a repository with your experiences I can offer solutions in the form of PR.

Added an example of a single root for the Avalonia application

Sorry to bother you yet again. Getting "Cannot parse a compiled binding without an explicit datatype..." errors. And if I use uncompiled bindings, nothing loads.

I'm finding it hard to get working, maybe my vanilla Avalonia knowledge is just too limited. I'm thinking about giving up and using Winui3/M.E.DI instead.

That being said, here's my current composition and AppDataContext class.

internal partial class Composition
{
 void Setup() => DI.Setup(nameof(Composition))
 .DefaultLifetime(Singleton)
 .Bind<ITodoDataProvider>().To<DummyTodoDataProvider>()
 .Bind<ITodoService>().To<TodoService>()
 .Bind<MainWindowView>().To<MainWindowView>()
 .Bind<TinyTaskWindowView>().To<TinyTaskWindowView>()
 .Bind().To<TinyTaskWindowViewModel>()
 .Bind().To<MainWindowViewModel>()
 .Root<AppDataContext>("Root");
}
public class AppDataContext(TinyTaskWindowView tinyTaskWindowView,
 MainWindowView mainWindowView,
 TinyTaskWindowViewModel tinyTaskWindowViewModel,
 MainWindowViewModel mainWindowViewModel)
{
 public TinyTaskWindowView TinyTaskWindow => tinyTaskWindowView;
 public MainWindowView MainWindow => mainWindowView;
 public TinyTaskWindowViewModel TinyTaskVM => tinyTaskWindowViewModel;
 public MainWindowViewModel MainVM => mainWindowViewModel;
}

From app.axaml.cs

if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop 
 && Resources["Composition"] is Composition compo
 )
 {
 CurrentWindow = compo.Root.MainWindow;
 TinyTaskWin = compo.Root.TinyTaskWindow;
 desktop.MainWindow = CurrentWindow;
 TinyTaskWin.Activate();
xaml: 
	<Application.Resources>
		<local:Composition x:Key="Composition"/>
	</Application.Resources>
 }

And here is MainWindowView

xmlns:app="clr-namespace:Rzy.AVA"
		x:DataType="app:Composition"
		DataContext="{Binding Root.MainVM}">
	<Design.DataContext>
		<vm:MainWindowViewModel/>
	</Design.DataContext>
	<TextBlock Text="{Binding Greeting}" 
			 HorizontalAlignment="Center" VerticalAlignment="Center"/>

No worries, every such question helps to identify questionable use cases of Pure.DI.

I assume the problem is in the xaml:

x:DataType="app:Composition"
DataContext="{Binding Root.MainVM}">

I'm not sure you've defined the data context correctly here. In the example, the data context is defined by an instance of the Composition class from the resources.
I think these types in DataType and in must DataContext are the same.

If you took the example as a basis, there:

x:DataType="avaloniaApp:Composition"
DataContext="{StaticResource Composition}"

DataContext="{StaticResource Composition}" means to take a generic instance of the Composition class from the resources as the data context. x:DataType="avaloniaApp:Composition" - means to use compiled bindings of the specified type. Further all bindings can be performed based on the data context.

If you share your example I will try to find the problem exactly.

My last experience with WPF was 10 years ago, and I'm only familiar with Avalonia from simple examples :)