You can have a Facebook shop and Instagram shop without installing the Facebook & Instagram app (Facebook sales channel) on your Shopify admin page and without using the Shopify (Facebook sales channel) Product catalog in your Facebook Business/Commerce Manager.
In general, for FB and IG shops, any Facebook catalog, including a catalog exclusively with the Flexify feed, can be used as long as it is set up correctly.
It is a more manual setup but it is perfectly possible and we think it's even the better option.
Setting up the pixel is the only missing piece that we do not provide and where your own pixel is needed.
What we recommend if you want to use Flexify for your Facebook shop:
1. The availability of your products has to be set to include "Online store channel".
2. To create a unique catalog for our feed. The tutorial "How to set up your Flexify catalog" is available here.
Important: If you have already installed the Shopify Facebook & Instagram app (sales channel), for Flexify to work correctly with the automatically generated Shopify Product catalog our Extension mode is needed.
3. To have an enhanced catalog. Facebook calls product catalogs that have products with category-specific attributes in it an enhanced catalog.
[Update] The usage of product tags to define a Facebook product category is not recommended anymore. We recommend the usage of Shopify product categories or types, or even Google product categories instead. Shopify product types can then be mapped to product categories.
So, when do you need the Shopify (Facebook sales channel) Product catalog?
If you want to have a single place for everything: digital storefronts FB shop and IG shop, store catalog, selling products directly from the Instagram profile and Facebook page, and checkout on the social platforms without leaving them.
By the way, you can connect your FB page with your WhatsApp business profile not only to communicate with your customers but also to showcase products or services while creating a mobile storefront with a catalog.
The advantage of using the Commerce Manager with the Shopify catalog is that's a single place enables you to use checkout for eCommerce purchases, as well as handle inventory, orders, payouts, and more.
The other way with a single Flexify catalog can guarantee the flawless operation of the app, the features like showing the cheapest variant, setting price modifier, segmentation of the products, optimization of the images, and many more, described here.
Also, customers can browse products on Facebook or Instagram and purchase them directly to the online store. A working solution that we highly recommend.