RFMD’s RF6504 front-end module is designed for 433MHz to 470MHz AMI/AMR systems. The transmit port provides a power amplifier with nominal output power of 30dBm and gain of 15dB. The receiver ...

In essence, you connect a common 433 MHz receiver module to an ESP32 or ESP8266 microcontroller, and have it wait until a specific device squawks out.