RabbitMQ has a management interface that shows real-time information about your queues, including how many messages are on them, how many acks/nacks it recorded, how many consumers are on the queue, etc. If you're deploying RabbitMQ using Docker, there's a separate image that has the management interface. I'll attach images and links later.

Edit

Here's a screenshot of the management interface. Notice the graph that shows 850 messages in "Ready" state and 0 in "Unacked" state. The "Ready" messages are waiting to be delivered. If any had been delivered to a consumer, but the consumer hasn't acked the message, the "Unacked" count would be higher.