penetration test – Is there a way to detect if a USB host has actually loaded the driver of the USB device that I have connected?

Suppose I have a device that is a black box for me. It could be an IoT device that I would like to examine during a pen test. Suppose further that the device has a USB port. One thing I would like to know, is:

If I connect a USB device, say an HID device, is the corresponding driver loaded or not?

For keyboards, I thought it might work to play with Numlock. Since the Numlock LED is controlled by the driver, I could simply press Numlock to see what's going on (does it stay off, does it light up?). If nothing happens, the driver may not be loaded.

Is there a general approach to this? Is there a generic USB message indicating that the device can now be used?

The bottom line of my question is whether a device supports arbitrary USB devices or not, which could pose a security risk.