It includes an additional charger, wich costs 25$ in the ifixit store, + has both hdmi and Displaylink, both of wich can reach 4k 120hz. Also 1Gb/s ethernet port and 3 usb 3.1. Also firmware updates and support from valve.
my official dock likes to not recharge it often. I have to look and replug in the usbc to the dock to and check to make sure its charging. I actually now just plug the usbc directly to the deck as then I don't have to fuss with it so much.
I bought a 3rd party dock but soon realized it doesn’t pass ARC signals over HDMI… so when the dock is plugged into my receiver it fucks up all the auto-power on and volume control stuff. I believe the official dock has this supported in its firmware.