Prometheus supports writing (replicating) data to a remote endpoint on a per scrape basis with a protocol called remote-write. You can pretty easily set that up on any Prometheus instance. There are quite some implementations to receive those remote-write requests: https://prometheus.io/docs/operating/integrations/#remote-en...

You're probably exactly looking for something like that. In fact, I've given a talk about a similar scenario at the KubeCon San Diego: https://www.youtube.com/watch?v=FrcfxkbJH20

Disclosure: I work on Thanos and Thanos Receiver which implements that protocol.