Home Automation System Based On Raspberry Pi Pico

To develop an advanced home automation system, we need to have the following things

Raspberry Pi Pico - Raspberry Pi Pico is a robust microcontroller that comprises features like RP2040 Dual Core ARM Cortex-M0+ clocked at 133MHz, 256KB RAM, 30 GPIO pins, and a broad range of interfacing options.
Raspberry Pi Pico Relay Board - Raspberry Pi Pico Relay Board is developed with the potential to control up to 4 appliances and loads up to 240V AC@ 7A, 30V DC@ 10A. It is easy to use as one needs to just stack the Raspberry Pi Pico on it.
HC-05 Bluetooth Module - It is a serial Bluetooth module for the microcontrollers with an operating voltage of 4V to 6V and an operating current of 30mA. It works with Serial communication (UART) and TTL compatibility.
USB Cable - For Programming with Raspberry Pi Pico.

Stack Raspberry Pi Pico on 40 pin Pico header of Pico Relay board.
Connect HC-05 Bluetooth module RX and TX pin on Pin GP0 and GP1 of external header of Pico relay board. Follow below circuit arrangement to connect everything together.
Now copy below code and paste it in any micropython supported ide (for example: Thonny) and select interpreter as MicroPython (Raspberry Pi Pico).
Click on Green play button to run program on Raspberry Pi Pico.
Now use any Serial terminal app from play store to send data to your Bluetooth module. Send "1" to turn on Bulb and send "2" to turn off Bulb.