By ethernet cable. Verizon router should preferably be in bridge mode (ask/ search Verizon how). If the Verizon router does not have a RJ-45 port, it won't work with Nest Wifi.
General setup guide:
Thanks for letting us know, In most cases, having your ISP router broadcast its own Wifi does not affect your Google Wifi's performance. But it can be an issue if you play online games or use port forwarding rules and Universal Plug and Play. If in any case it does affect your Google Wifi, we suggest contacting your ISP to set the router in bridge mode.
Neither have I. I have the new CR1000A Gateway and the verizon tech told me all i have to do is connect an Ethernet cable from my verizon router to my google nest router, then reboot both routers and everything should work fine. I did that but on my devices I still see both my Google network and my Verizon network. Is this normal? I have all my devices connected to the google nest wifi, and haven't experienced any problems (yet).