New From Google, an Ethernet Adapter for Chromecast

Ugreen USB-C to Ethernet RJ45 Adapter 1000Mbps with Charging Port (Works with new Chromecast 4K with Google TV) - GeeWiz

The new Chromecast with Google TV will get an Ethernet adapter, but it will cost $20

Ethernet Adapter for Chromecast with Google TV at Rs 1999/piece, Bavdhan, Pune

Hardware devices offer a LAN connection to streaming sticks

Ethernet Adapter w/ Power Compatible with Google Chromecast Streaming Sticks for a wired LAN internet connection

Review of the Ethernet Adapter for Google Chromecast

The Ethernet Adapter for the new Chromecast with Google TV will cost $15/£15 (links in comments) : r/Chromecast

Google launches a Chromecast Ethernet and PSU adapter - Network - News - HEXUS.net

Ethernet adapter for Chromecast with Google TV shipping - 9to5Google

Use a USB-C Hub to Upgrade Your Chromecast With Google TV