How to build a "pure" Onion architecture of an ASP.NET application?

Question

ASP.NET

Hey Habr! Now I am actively writing a small project (online bookstore) on ASP.NET MVC (.NET Framework). I chose Onion as the architecture. I understand that a three-layer one is probably better, but I want to study this particular way of organizing a project. So, in the "core" I have Domain Models, this is understandable. Then, at the Domain Services level, I have the IRepository and IAsyncRepository interfaces, everything is also clear here. Then I started having problems .... At the ApplicationServices level, I have classes that implement the IRepository and IAsyncReository interfaces, DbContext is also located there (I use EF6 as an ORM). Questions: is it right to place specific repository classes in the application services layer? Or is it better to leave them at the level of domain services? Just on different resources / diagrams in different ways. And one moment: at the heart of the application, I have the OrderedProduct class and the Cart class, in which I have the logic for adding a new product to the cart. Is it right to leave these classes in the layer of domain models, because this is a subject area, on the other hand, there is already some kind of logic (which will be changed / expanded in the future) and this is already an application service?

PS I understand that the division at the level in software architectures is very conditional, you can implement it in different ways ... But I still want to get the opinion of people who have encountered this and get their opinion so that in the future I don’t have to refactor the entire project completely .Thank you for your attention.