Condolences, without that itty bitty, easy to lose piece of plastic and metal, your lovely keyboard is reduced to a $60 paperweight. Thanks, Microsoft! I have two of these poor dongleless things in my computer room.
I've seen a few enterprising fellows online who swapped out keyboard controllers and modded the sculpt with a Bluetooth keyboard controller, but generally most people won't have the know how or proficiency with a soldering iron to attempt these fixes.
If only this keyboard didn't type so %#*@ good!