Adressing USB cameras via WebCamTexture in Android

While WebCamTexture.devices provides a list of all available devices while running Unity on Windows, including USB attached to the PC and those of an Android devices connected thru Unity Remote, it seems not to be able to address USB cameras attached to an Android device after being compiled. I'm using Unity 2019. I have already seen similar questions in the internet but no answer. I would need some method to "enrich" WebCamTexture.devices with the external USB cameras in Android.