I've searched a bit how to extend Entities (i.e. product) and find in doc this article:
The main problem with this is when a new release comes: the upgrade may be hell, if lots of customization occured; I've found this thread ob about 2 years ago https://www.nopcommerce.com/boards/t/29527/extending-entities-without-editing-the-nopcommerce-330-core.aspx
Has anything changed since then? Is there a supported, or raccomanded, way to achieve this goal?