How do I add a custom column to the product list?

As the products list is a resource list you can add a custom column like this:

More information on resource lists can be found in the article "How do I extend an existing Resource List?".

<?php

namespace Acme\MyModule;

use Aero\Admin\ResourceLists\ProductsResourceList;
use Aero\Common\Providers\ModuleServiceProvider;

class ServiceProvider extends ModuleServiceProvider
{
   public function setup()
   {
       ProductsResourceList::extend(function (ProductsResourceList $list) {
           $list->addColumn('My Column', function ($row) {
               return $row->id;
           });
       });
   }
}