How to bind multiple controls to a single model value in Avalonia UI MVVM without making the model object contain [ObservableProperty]

This example is a little contrived but it illustrates the point. It is an app that can toggle between three preset volume levels by clicking the row in the data grid and allow editing of the selected value.

This uses Avalonia and the MVVM Community Toolkit.

Main Window View Model contains a model object, in fact an observable collection of model objects,

using CommunityToolkit.Mvvm.ComponentModel;
using QuestionApp1.Models;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace QuestionApp1.ViewModels
{
    public partial class MainWindowViewModel : ViewModelBase
    {
        public ObservableCollection<VolumeSetting> VolumeSettings { get; }

        [ObservableProperty]
        public VolumeSetting? selectedVolumeSetting = null;

        partial void OnSelectedVolumeSettingChanged(VolumeSetting? value)
        {
            AnyRowIsSelected = (value != null);
        }

        [ObservableProperty]
        public bool anyRowIsSelected = false;

        public MainWindowViewModel()
        {
            var volumeSettings = new List<VolumeSetting>
            {
                new VolumeSetting(25),
                new VolumeSetting(50),
                new VolumeSetting(75)
            };
            VolumeSettings = new ObservableCollection<VolumeSetting>(volumeSettings);
        }
    }
}

All the UI is in the MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="using:QuestionApp1.ViewModels"
	    xmlns:m="using:QuestionApp1.Models"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="QuestionApp1.Views.MainWindow"
        x:DataType="vm:MainWindowViewModel"
        Icon="/Assets/avalonia-logo.ico"
        Title="QuestionApp1">

    <Design.DataContext>
        <vm:MainWindowViewModel/>
    </Design.DataContext>

    <StackPanel Margin="20">
	    <Label>Volume:</Label>
	    <Slider Value="{Binding SelectedVolumeSetting.Volume}" IsEnabled="{Binding AnyRowIsSelected}"></Slider>
	    <NumericUpDown FormatString="N0" Minimum="0" Maximum="100" Increment="5" Value="{Binding SelectedVolumeSetting.Volume}" IsEnabled="{Binding AnyRowIsSelected}"></NumericUpDown>
	    <DataGrid Margin="20" Height="200" ItemsSource="{Binding VolumeSettings}" SelectedItem="{Binding SelectedVolumeSetting}"
			      AutoGenerateColumns="False" IsReadOnly="False"
			      GridLinesVisibility="All"
			      BorderThickness="1" BorderBrush="Gray">
		    <DataGrid.Columns>
			    <DataGridTemplateColumn Header="Volume">
				    <DataGridTemplateColumn.CellTemplate>
					    <DataTemplate DataType="m:VolumeSetting">
						    <TextBlock Text="{Binding Volume, StringFormat='{}{0}'}"
						      VerticalAlignment="Center" HorizontalAlignment="Center" />
					    </DataTemplate>
				    </DataGridTemplateColumn.CellTemplate>
				    <DataGridTemplateColumn.CellEditingTemplate>
					    <DataTemplate DataType="m:VolumeSetting">
						    <NumericUpDown Value="{Binding Volume}"
						       FormatString="N0" Minimum="0" Maximum="100" Increment="10"
						       HorizontalAlignment="Stretch"/>
					    </DataTemplate>
				    </DataGridTemplateColumn.CellEditingTemplate>
			    </DataGridTemplateColumn>
		    </DataGrid.Columns>
	    </DataGrid>
    </StackPanel>
</Window>

The UI is repeated twice. The top has a non-observable model object, it just contains a simple property for the value it contains

namespace QuestionApp1.Models
{
    public class VolumeSetting
    {
        public int Volume { set; get; }

        public VolumeSetting(int volume)
        {
            Volume = volume;
        }
    }
}

The bottom UI makes this attribute observable,

public partial class ObservableVolumeSetting : ObservableObject
{
    [ObservableProperty]
    public int volume;

    public ObservableVolumeSetting(int volume)
    {
        Volume = volume;
    }
}

Problems

With non-observable model-object I get the three issues:

1. When the slider edit the value the other control to not update
2. When the numerical up and down edits the value the other control to not update.
3. When editing the value in the table value the other controls to not update.

These are all fixed by switching to an observable object.

I have heard that is bad practice, but the code does not seem that bad too me.