Currently, the C api is dllimport'd into the normal class namespace (e.g. Efl.Ui.Button.efl_content.get). We should hide them so it becomes something like Efl.Content.NativeMethods.efl_content_get. (This may also help reduce the number of duplicated dllimports).
The dotnet patch from D8069 replaced the DLLImport's in the public API class with some fields in the NativeInherit classes. I think this could be marked as resolved it that seems enough.
About actually hiding them from the docs, have you checked https://dotnet.github.io/docfx/tutorial/howto_filter_out_unwanted_apis_attributes.html? In our case, one of the rules would be hiding the *NativeInherit classes.