It's easy to permanently ignore Shopify products from being shown as Fomo notifications.
Inside Shopify, visit the Edit page of a product you want to ignore, and simply add 'notify-ignore' as a product tag.
If you already see imported events of that product, navigate to the Events tab and delete the previous orders of that item.
Finally, visit the 'Design & Settings' menu. Update the 'Event Threshold' field to a new value in order to trigger a new import of orders in the events tab.