I haven't yet used NATS for IoT but based on the NATS documentation:
"In greenfield IoT deployments, when possible, we prefer NATS extended out to endpoints and devices for a few reasons. There are significant advantages with security and observability when using a single technology end to end. Compared to MQTT, NATS is nearly as lightweight in terms of protocol bandwidth and maintainer supported clients efficiently utilize resources so we consider NATS to be a good choice to use end to end, including use on resource constrained devices."
My personal view is that NATS is simply fantastic to use with your core systems to power an event-driven architecture due to its amazing performance and easy of use. As such if you are using NATS allover the place then why add a second system to manage and to transfer information in and out from. You can just use NATS instead to cover all your needs.