I am also interested in this topic. Does anyone have any info on this idea for an integration i.e. a Klaviyo plugin for NOP. We are probably going to be using v4.0
Maybe a dev on this forum would like to propose creating one or has maybe started one and not managed to finish it? I might be able to put some budget towards it.
Equally, I'm interested in a Bronto integration but that should be another thread so...