What is best starting point?
We have different plone's that interact through rest-api-calls and now want the receiving plone (called with POST or PATCH) use a RabbitMQ or similar.
Yes, you can use eea.rabbitmq.client to send messages from Plone to RabbitMQ (not sure it works with python3, yet - but it shouldn't be that hard to make it work).
Then, you will need Celery to extract and process that messages from RabbitMQ.