nats-serverand you only need 1 (or 3 or 5 if you want fault-tolerance against 1 or 2 simultaneous NATS server failures) of your NATS server(s) to be JetStream enabled for it to be available to all the client applications.
push(ordered) consumers to receive messages as fast as possible (for the selected replay policy) on a specified delivery subject or to an inbox. Those consumers are meant to be used to 'replay' rather than 'consume' the messages in a stream.
pullconsumers that are demand-driven, support batching and must explicitly acknowledge message reception and processing which means that they can be used to consume (i.e. use the stream as a distributed queue) as well as process the messages in a stream.