The nRF52840 MDK USB Dongle from Makerdiary is a small little dev board featuring an nRF52840 and plugging directly into a USB 2 A port. One of the things you can do with it is to sniff Zigbee traffic.
By default these days, the dongle will ship with the UF2 bootloader. Plugging the dongle in while holding the button pressed will trigger it and you will see a combination of USB mass storage device and serial port for programming.
Nordic Semiconductor provides a (closed-source) firmware and necessary Wireshark plugin on Github. Unfortunately I did not have much success converting it to uf2 and flashing it with the UF2 bootloader, so let's go back to the Open Bootloader we can use with Nordic's tools.
To do so, we can follow the instructions. I'm doing this on powershell and with a dedicated virtualenv:
> python -m venv venv > . .\venv\Scripts\Activate.ps1 > pip install adafruit-nrfutil > adafruit-nrfutil.exe --verbose dfu serial --package .\nrf52840_mdk_usb_dongle_open_bootloader_v1.2.0.uf2.zip -p COM7 -b 115200 --singlebank
The referenced zip file comes from the same repository as the instructions. The COM port depends on your system -> check device manager.
With the new bootloader, we can now simply follow the instructions from Nordic and use nRF Connect for Desktop to flash the firmware.
Make sure you tell Wireshark about your network's key (eg. from the configuration.yaml if you're using Zigbee2MQTT) to get the packets nicely decoded.