Is there anyway to get the apps a device is using? I have tried many variations of device.getInUseBy() with no luck.
This information is not progmatically available as far as I can tell.
You can find documented methods available here -- guessing at names is unlikely to work unless you make good guesses.
https://docs2.hubitat.com/developer/device-object
(but this isn't available on anything I can see beyond this, either)
Is there any way to get this ability added to the device object?
That's a question for gopher.ny, who will probably see this eventually, but normally they like a compelling use case.