You've got that right. A sort of gateway appliance would be far better, more likely a pair for any telemetry that matters. It'd have the advantage that the monitoring devices are specialized in their individual requirements for each use. And then your edge gateway appliance can be specialized in its approach to analyzing, bundling, and posting to home base. Last thought is using the appliance to push updates to the instruments while the gateways are updating themselves via "The Cloud." Come to think on it, it's very much the branch office architectural approach.
That's how I'd approach it. More general purpose edge gateway that happens to get its purposes and security from the Kubernetes approach.