When it comes to automated testing, Zephyr's Native Simulator is worth your consideration. The next release of Zephyr will include offloaded sockets for Native Simulator, which means CI tests that complete many times faster than their native-hardware equivalents.
Golioth includes remote logging as a core feature. However, for devices operating on a cellular network, you don't want to use bandwidth for logging messages unless they are really needed. This post discusses how to use Golioth and Zephyr RTOS to set device logging levels remotely.
With a bit of planning, you can make sure that your IoT devices stay in sync with the cloud and behave in a predictable way for your users. The concept uses a "desired state" that is watched by the device for changes from the cloud. The device then reports back its actual state as a separate collection of data.