I am using the Zigbee2mqtt firmware on a CC2531 sniffer connected to my Raspberry Pi. The CC2531 sniffer can act as a Zigbee coordinator, and Zigbee2mqtt bridges the gap to home automation tools like Home Assistant.

A Raspberry Pi Model A+ with a CC2531 sniffer connected via USB
The CC2531 sniffer has a Zigbee radio and communicates with its host via USB.