NATS is a simpler PUB/SUB system that delivers in the UNIX spirit of small composable parts. Apache Pulsar or Apache Kafka deliver the banana, the ape holding it and the rest of the jungle.
Check out Liftbridge (https://liftbridge.io) as a way to add these capabilities to NATS.
your FAQ still says it's not production ready? Is this still the case, I've been keeping my eye on this project
It's getting very close. I had wanted to make a production-ready 1.0 release before the end of the year, but we're in the process of switching from protobuf to flatbuffers. Once that is complete, a stable release will be made.