How to add computed property to existing IdentityUserDto? #2231

I would like to create a computed property for the purpose of using this in the navigation dropdown as the display property. I think this scenario could be pretty common, especially with the desire to often add the IdentityUser as a navigation property to one of your own entities. So for that purpose I wanted to add a "FullName" property to IdentityUserDto, instead of now only being able to choose between Name and Surname that is available on this type (other properties are of course available, but not relevant to the question).

Having already been successful in adding multiple 'regular' properties to the IdentityUser entity and the IdentityUserDto class, I am thus familiar with the various options, and also what is currently available as information from the documentation. However, how could we achieve this type of extension property? I am unable to figure out how to access the Dto instance itself when providing the configuration, so I am confused how I can create my property.

As a reference, this is how I would declare the property if the Dto class was my own:

public string FullName => string.Join(" ", string.Empty, Name, Surname).Trim();

or as a common variation using interpolation:

public string FullName => $"{Name} {Surname}).Trim();

What do I need to provide to the configuration parameter to achieve the equivalent result?

user.AddOrUpdateProperty<string>(UserConsts.FullName, options => options.DefaultValue = <What should I use here?>);

I also looked at the DefaultValueFactory but this Func does not provide access to the referencing type.

Note: If this is currently not possible through the regular extension methods, is there any alternative or other work-around to achieve something similar?

Thanks for your time and effort.