The device path for devices cannot be guarateed as they are loaded in arbitrary order by systemd.
With the exception of mouse and keyboard they are usually connected automagically.
If the device is a removable disk containing e.g. games you should take look at mounting the device using a combination of systemd mount and automount units.
This topic explains in detail how to achieve an automatic mounting of a USB device.
I guess you can use the virtmanager setup to attach a path to a virtual maching.