Maybe I was unclear about my question. The documentation I was referring to is
https://learn.microsoft.com/en-us/dotnet/framework/wpf/advanced/read-only-dependency-properties
And here is an example of what a regular ReadOnly property might look like:
Public ReadOnly Property FirstPlusSecond() As Integer
Get
Return Me.First + Me.Second
End Get
End Property
Note that the Get returns a generated value (it does not use GetValue like a regular DependencyProperty would). I want to be able to bind to this property in my XAML. How would I make this property bindable?