It's interesting that the platform has grown so much. I paused reading at the inbox feature, so there's more to dig in to. I enjoyed reading the topic guide, and I think it was pretty intuitive when I started using it.
Outside of work projects, I maintain a public transit info site, where I either estimate or process telemetry feeds to generate trip updates, alerts, vehicle positions. NATS pub:sub works so well for me (along with tidwall:tile38 for geofencing). The site isn't that large, but a large volume of messages pass through NATS every few seconds. It's really been a great reliable small piece of technology.