Hi @Bran,
Welcome to the community. Even though I can't answer this question (not a Klaviyo employee) I do understand that if you're using this you're also not the average webshop and you probably have some customizations done on your end.
With that said, you don't need the Klaviyo plugin to be able to run Klaviyo. With a developer at hand I would suggest to built it yourself. Checkout https://developers.klaviyo.com/en/v1-2/docs/guide-to-integrating-a-platform-without-a-pre-built-klaviyo-integration and https://developers.klaviyo.com/en/reference/api_overview about how to setup a custom integration.
The level of flexibility you'll get from this is much bigger than using the plugin. Even though its a good plugin.
Setting this up should not take weeks for a developer, everthing is very well documented and the level of events and tracking needed is overseeable.
Hope this helps!
Omar Lovert // Polaris Growth // Klaviyo Master Platinum Partner
We help with e-commerce growth through CRO, Klaviyo and CVO
Helping E-commerce brands maximize Lifetime Value & Profits with Klaviyo, CRO & CVO - Get your free Audit - https://link.polarisgrowth.com/free-audit