Amazon MQ

Related: SQS, SNS, Hybrid
VPC Based (or Direct Connect (DX)), not public
No native AWS integration

Open source message broker.
Based and on managed Apache ActiveMQ - Wikipedia
Jakarta Messaging (JMS API).. and AMQP, MQTT, STOMP, OpenWire (binary protocol) if you need to support one of these, MQ is a way to go.
Provides queues and topics
Has both one-to-one and one-to-many communications
Either Single Instance Broker (for test, dev) or Highly Available Broker (Active/Standby)