Design a microcontroller-based or similar (e.g. Raspberry Pi, Arduino etc.) smart home device, with the following capabilities, but not limited to:

1. Multi-channel temperature and relative humidity data logging.
2. User-configurable alerts and actuation (e.g., thermostat functionality) on a local or remote device for all input sensor data.
3. Semiconductor or mechanical relay-based high-side drivers for power devices, with pre-programmable functions and timing schemes.
4. Wi-Fi-enabled communication.
5. A web-based GUI accessible via PC or mobile device.