How can i bind to my viewModel inside my ItemTemplate?

<ItemsRepeater
    x:Name="ChannelList"
    ItemsSource="{x:Bind ViewModel.ChannelSource}">
    <DataTemplate x:Name="ChannelTemplate">
        <Border
            Margin="0,0,0,10"
            BorderBrush="LightGray"
            BorderThickness="1">
            <StackPanel
                Orientation="Horizontal"
                Margin="10"
                Spacing="20">
                <!--content-->
                <TextBlock
                    Grid.Row="0"
                    Grid.ColumnSpan="2"
                    HorizontalAlignment="Center"> 
                    <Run Text="Kanal: " />
                    <Run Text="{Binding ChannelId}" />
                </TextBlock>
                <Button
                    Grid.Column="0"
                    Grid.Row="1"
                    HorizontalAlignment="Left"
                    Content="Start" />
                <Button
                    Grid.Column="1"
                    Grid.Row="1"
                    HorizontalAlignment="Right"
                    Content="Stop" />
                <Button
                    Grid.Row="2"
                    Grid.ColumnSpan="2"
                    HorizontalAlignment="Center"
                    Content="Kanal Entfernen"
                    Command="{Binding ??}" />
            </StackPanel>
        </Border>
    </DataTemplate>
</ItemsRepeater>

I wanted to bind inside my item template, but i could not figure out how to do this. Normal x:Bind or Binding does not work. Any suggestions?

This is a known issue with ItemsRepeaters. But lucky for us, there's a workaround.

I'm sure that this will be fixed someday but for the moment:

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using System.Collections.ObjectModel;

namespace WinUI3App;

public partial class Channel : ObservableObject
{
    [ObservableProperty]
    private int channelId;

    public ViewModel? Parent { get; set; }
}

public partial class ViewModel : ObservableObject
{
    [ObservableProperty]
    private ObservableCollection<Channel> channelSource = new();

    public ViewModel()
    {
        channelSource.Add(new Channel { ChannelId = 1, Parent = this });
        channelSource.Add(new Channel { ChannelId = 2, Parent = this });
        channelSource.Add(new Channel { ChannelId = 3, Parent = this });
    }

    [RelayCommand]
    private void RemoveChannel(Channel channel)
    {
        ChannelSource.Remove(channel);
    }
}

Note: You can use x:Bind by setting x:DataType of DataTemplate.

<Page
    x:Class="WinUI3App.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="using:WinUI3App"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
    mc:Ignorable="d">
    <Grid>
        <ItemsRepeater
            x:Name="ChannelList"
            ItemsSource="{x:Bind ViewModel.ChannelSource}">
            <DataTemplate
                x:Name="ChannelTemplate"
                x:DataType="local:Channel">
                <Border
                    Margin="0,0,0,10"
                    BorderBrush="LightGray"
                    BorderThickness="1">
                    <StackPanel
                        Margin="10"
                        Orientation="Horizontal"
                        Spacing="20">
                        <!--  content  -->
                        <TextBlock
                            Grid.Row="0"
                            Grid.ColumnSpan="2"
                            HorizontalAlignment="Center">
                            <Run Text="Kanal: " />
                            <Run Text="{x:Bind ChannelId}" />
                        </TextBlock>
                        <Button
                            Grid.Row="1"
                            Grid.Column="0"
                            HorizontalAlignment="Left"
                            Content="Start" />
                        <Button
                            Grid.Row="1"
                            Grid.Column="1"
                            HorizontalAlignment="Right"
                            Content="Stop" />
                        <Button
                            Grid.Row="2"
                            Grid.ColumnSpan="2"
                            HorizontalAlignment="Center"
                            Command="{x:Bind Parent.RemoveChannelCommand}"
                            CommandParameter="{x:Bind}"
                            Content="Kanal Entfernen" />
                    </StackPanel>
                </Border>
            </DataTemplate>
        </ItemsRepeater>
    </Grid>
</Page>

BTW, if you can use ListView or GridView instead of ItemsRepeater, you could do it this way.