Joomla picsell component customization

Hello this is a project about customizing Picsell component of Joomla. This is a great component overall but it lacks one basic thing: you can't set the menu items to link to a category/subcategory view. The way component is implemented right now you can make categories and sub-categories through component's admin cp but when it comes to menu setting, you can only set it show one or more categories (inserting their IDs separated with comma). This is not helping in cases of many subcategories because making a menu item for every single subcategory will lead to hundreds of submenu items.