In hardwired scenarios the port speed on individual consumer devices rarely exceeds 1G. Wi-Fi 6 Enterprise level AP's can get up to 9.6G of throughput in optimal conditions, but your speed is likely choked by the capability of the end device itself.
In the aggregate, you'll need piles of users to even remotely threaten utilizing 20G's.
Google Fiber uses passive optical networking, so it's a best effort, up to network.