[JimmXinu]

Originally Posted by chaley

You can do the same thing in a custom template function. Example:
...
Does this answer your question?

Yes, thank you.

It's not polished, obviously, but this does what I wanted:

template function:

def evaluate(self, formatter, kwargs, mi, locals, *fnargs):
	from calibre.gui2.ui import get_gui
    dm = get_gui().device_manager
	info = dm.get_current_device_information()
	v = ''
	if dm.is_device_present and info is not None:
		print(info)
		v = info['info'][4]['main']['device_name']
	return v

custom column template:

{:device_info()}

See attached screen caps for all the GUI settings.

ADDED:

Originally Posted by chaley

I could add a function that returns the connected device name, but it wouldn't be guaranteed to be the empty string for a time after a device disconnects.

chaley was right about that. I've updated the function above to also notice when the device is not present.