Review on 🔍 Acxico 1Pcs USB CC2531 Sniffer Board: Bluetooth 4.0 Wireless Zigbee Analyzer Module with External Antenna - Enhanced Connectivity and Monitoring Capabilities by Brad Schillings

I bought this because it had an antenna that still works pretty well. Works great with Zigbee2MQTT Home Assistant, but make sure you flash the firmware first, and you'll need either a Rasp Pi or a standalone debugger for that. It's relatively easy with a Rasp Pi, but you'll need to have a few jumpers to spare! If you can, buy a "bootloader cable" (search Amazon for "cc2531 Zigbee bootloader") or you'll break the replacement electronics (in my case, a small laser cat toy with motion detection has connectors that are small were enough to fit) Try to find connectors small enough to fit tiny pins. Mine are for the RasPi side but they are even smaller for the CC2531 but you can bend them if you need more space. Just search for "flash cc2531 without cc debugger" to see how the actual flashing is done.