Hello @chrisB  Yes,  it is possible.

You will have to write a custom JS code to add a clickeventlistener on the Klaviyo Popup form button.

This listener will check if Klaviyo button is clicked then you should be able to get the data of the form and save it in cookies.

Hey Max, Figured out a way around this using the Klaviyo Datalayer Event, then catching in GTM and using that to write to Cookie. I actually moved from Cookie to using a datastore to maintain strong PII and then only add the KL profile ID, and reference it.