Manufacturing cost per component versus number of components per integrated circuit, from
An overview of IoT device security and the role firmware plays in the overall software picture.
For microcontrollers, it's a bit different. Firmware often represents the entire software stack, due to limited memory and compute resources. Low-power sensors are more heavily customized for specific markets, so changing firmware is essential to building a proper solution. Small devices like freight tracking sensors don't communicate directly with the cloud, and need to work as a mesh network to...
Platforms like MinnowBoard are a great starting point for IoT edge hardware... as long as you lock down a few things in the firmware.