Configure AWS IoT Core, create an Amazon MQ queue for each device, and provision a certificate. Connect each device to Amazon MQ.

Deploy a Network Load Balancer (NLB) with an AWS Lambda authorizer, set up an MQTT broker on EC2 instances within an Auto Scaling group, and connect each device to the NLB.

Set up AWS IoT Core, create an AWS IoT thing for each device, provision a certificate, and connect each device to AWS IoT Core.

Establish an Amazon API Gateway HTTP API with an NLB, integrate the API Gateway with the NLB, use a mutual TLS certificate authorizer, run an MQTT broker on an EC2 instance targeted by the NLB, and connect each device to the NLB.