create type with %type or %rowtype

Hello.

It seems that I can not create a type with

create type my_type as my_table%rowtype;

or

create type my_type as my_table.my_column%type;

Correct? It seems to be a feature for plpgsql programing only, right?

But wouldn't that be a good thing to be able to do? Or would it cause
too many problems?

Best regards