If you already know about Facebook Shops then you’re ahead of me as I’m just learning about them. Basically you set up shop on Facebook and fill it with “collections” (similar in principle to Zazzle collections). People can then click a product, get taken to the Zazzle product page, do any personalization and then buy.
One of the things that makes it easy to get products into a shop’s inventory (aka “catalogue”) is via data feeds. Once you’ve got one or more of them pulling products from Zazzle into the catalogue then you can create subsets of the catalogue (aka “collections”) that then appear in your shop.
When you’re creating these collections (Fb calls them “sets” when you’re setting them up - why do they confuse things by using different terms, gah!) you can choose the products to go in them manually or by using a filter.
Facebook allows for named filter fields such as:
custom_label_1
color
gender
and with them you can select products that have those field contents set to specific values (eg create a set containing products where the gender field contents are set to female).
The standard Nifty feed doesn’t allow for those fields so I’m creating one specifically for Facebook data feeds that does include them.
The way you’ll use the feeds is to set up a pull in the Nifty Promo Control Panel, say for ladies’ t-shirts, and in the new tool section for it, you’ll set the new gender field contents to female. You’ll then be given the data feed url to use in the appropriate place on FB.
You’ll do similar for lots of different pulls and your “catalogue” on FB will be made up of the results of all those different feed urls, each with the filter field settings you decided on. Remember, this is so you can create the collections of just those product designs you want.
Then, when you’re creating sets (ie collections) for your shop on FB, you’ll be able to filter products from your catalogue and so get just those products you want into each FB shop collection you create.
It’ll need some thinking ahead but the mechanism is there to allow you to do shop collections made up of halloween, thanksgiving, christmas etc product designs.
Sorry if it all sounds a bit garbled right now but as I make progress, I’ll be able to write more clearly about it and give screenshots and examples.
Meantime, here’s a fairly ok article about setting up shop on FB. It’s not perfect but goes a long way: https://www.websitebuilderexpert.com/building-online-stores/how-to-set-up-a-facebook-store/
Happy to answer questions 
(Note that the usual Nifty terms apply - if you have a Nifty subscription, the referral id used in all links will be yours (but you’ll get clean links if you’re in the Promoter Program). If not, half of them will use yours and the other half, mine (based on a computer coin toss).
You always come up with something to work with.