I want to have the option to add a ToolTip for column, 

 <telerik:DataGridTextColumn IsFrozen="True" HeaderText="BirthDay"
                                            DataMemberBinding="{Binding BirthDay}"
                                            ToolTipProperties.Text="{Binding BirthDay}" />

Scenario: I want to bind two properties to a column, So I created Text column and set DataMemberBinding property to binding these two properties,

<telerik:DataGridTextColumn HeaderText="Country">
                    <telerik:DataGridTextColumn.DataMemberBinding>
                        <MultiBinding Converter="{StaticResource MultiConverter}">
                            <Binding Path="Country" />
                            <Binding Path="City" />
                        </MultiBinding>
 </telerik:DataGridTextColumn.

Add FontAutoScalingEnabled property to the header, textcell, groupheader, where font size can be set.

for the Label there is such property https://learn.microsoft.com/en-us/dotnet/maui/user-interface/fonts?view=net-maui-8.0#disable-font-auto-scaling that allows you to disable the text scaling

Provide support for nested properties with null values. 

Currently when using the following scenario: null ref exception is throw, when manager is null:

private Person _manager;
public Person Manager
{
    get { return _manager; }
    set { UpdateValue(ref _manager, value); }
}

<telerik:DataGridTextColumn PropertyName="Manager.Name" 
                            HeaderText="Manager"/>

Provide support for null values when nested properties are used in datagrid columns.

The DataGrid Search As You Type feature provides search text highlighting through the CellContentStyle property of the columns.  

CellContentStyle is taken into account only for the default columns, so when you specify a custom CellContentTemplate or use a TemplateColumn currently the search text highlighting is not applied.