I'm on Google Fiber and I've found other users coming to the same conclusion and unfortunately you can't substitute their router and maintain TV service.
I'm in the same situation in Australia with the supplied Telstra Cable Modem/Router. However in my case, and maybe yours, I don't need to substitute the Telstra router with another one, I can just put it into bridge mode, which turns it into a plain modem. Then I can add a new router behind (downstream from) the Telstra modem, connecting via the WAN port on the router, and have full functionality of the new router, whatever I happen to chose to use, be it just a better router, or a DD-WRT or other flashed router.
I don't have that setup at the moment, because I don't need to, but many people in Australia do just that to get a better router. The Telstra service isn't affected. An ISP Router in bridged mode, operating just as a modem, will forward all packets, including WOL packets, to the new router untouched. The new router can then be made to do what you wish, including Wake On WAN.
Perhaps you could do the same with Google Fiber?