nRF52840-Dongle firmware for pyACI (BLE Mesh)

We want to control the BLE Mesh network from the linux.
As we understand the only one way to do it now - pyACI https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.meshsdk.v3.1.0/md_scripts_interactive_pyaci_README.html?cp=5_2_2_3_1
But i can't found the firmware working with this script. It just doesn't described.
Where i can found the firmware for nRF52840-Dongle?