Hey,

I have been toying with this myself, I work on shopify as well. 

What are you trying to achieve specifically?

I have been considering if there is value using the customer events function in shopify to trigger page events without having to load on-site pixels/etc. 

im using for a custom GA4 and segment profile at the moment, but could never crack the Klaviyo side. 

Also here is the custom API docs for KL. 
 

https://developers.klaviyo.com/en/docs/custom_integration_faqs

There isn’t one specific task in particular.

We have always used the integrated solution which has been fine for some time but recently there have been cases where we need more flexibility like a custom back in stock feature when the products have inventory but we are labelling them out of stock for a business case. Another is just using lots of individual lists for similar tasks where I think and more flexible solution that is less work to manage is probably possible. Somebody else manages Klaviyo in this business so I’m a bit new to a lot here.

 

Do i need to set up an app or will the connection be authenticated by the klaviyo integration already there?

I think to auth with KL you will need your API details form KL. Standard api auth setup apples 

if your firing the JS you only need the store code 

There is probably a couple of ways to do the above. 

you could either hide the Div based on tag or something. 
 

or you could adjust the snippet (based on back-in-stock) to use a different variable/etc. 

ie: if it’s currently looking at the add to cart button (and the change from active to inactive), there is nothing to say you couldn’t create another button based on your logic and point the snippet to that