In case someone else stumbles across this with the same questions, this is what worked for us: Fleet managed elastic agent: Kubernetes Prometheus Metrics Autodiscover
Unfortunatly it’s not well documented and if you don’t have deep knowledge of Kubernetes it is not obvious how to do it.
Basically the Agent has the ability to autodiscover Pods with their respective IPs, annotations and so on. You can use this information in the Prometheus Integration to autodiscover any metrics-endpoints the same way a Prometheus does it.