Service mesh and Async services
Please note that Istio can control non-HTTP protocols on top of TCP, including providing Mutual TLS Authentication. See this example of mTLS for HTTPS (treated as opaque TCP) - https://preliminary.istio.io/docs/tasks/security/https-overlay.html.
I am not familiar with AMQP, but since it is a protocol on top TCP, it should be possible to control it by Istio as opaque TCP.
Apparently there is WIP to add Async (Event driven) messaging to Envoy Proxy through Kafka filter: https://github.com/envoyproxy/envoy/issues/2852
Also good summary on using a Service Mesh for Event-Driven Messaging here: https://www.infoq.com/articles/service-mesh-event-driven-messaging