That’s exactly right. There all all sorts of read-only architectures where the device can be monitored without every directly accessing it:

- The device’s control has a radio transmitter that emits its readings, but no receiver. Listen for those messages to monitor it but there’s not a physical path to reply to it.

- The device’s controller writes a database or message queue. Its code never reads from that source. Monitors listen to those messages.

And many, many similar methods with the same core concept: the item transmits its status but doesn’t have a method to receive replies. You just have to commit to using any one of those thousands of mechanisms.