zephyrproject-rtos/zephyr ? reverse-engineered prompt

Build me a project using the Zephyr operating system. I'm looking to create something for a small, low-power device, maybe a custom wearable or an IoT environmental sensor that needs to be secure and efficient. I know it's designed for resource-constrained hardware, which is perfect for what I have in mind.

It's really important that this has good support for Bluetooth, especially Bluetooth LE, since my device will likely be battery-powered. The setup seems a bit complicated with all the different hardware architectures and build tools. Could you please set up a basic, working foundation for me? You should look at the official getting started guide and the code samples to figure out the right way to initialize the project for a generic target. Let's just start with a simple demo application that I can build upon.