AvaloniaPages/AvaloniaApplicationPages/Views/Page2.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
			 xmlns:vm="using:AvaloniaApplicationPages.ViewModels"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
			 x:DataType="vm:MainWindowViewModel"
             x:Class="AvaloniaApplicationPages.Views.Page2">
	<StackPanel>
		<Button Command="{Binding toPage1}">Назад</Button>
	</StackPanel>
</UserControl>