if you go into the network configuration of the new mesh system, you can rename the network and password to anything you like. as long as those both match, all devices that were connected to your old router will automatically connect.
this is what i did with all my smart devices. i was not about to reconnect 50+ things because of a new name.
open google home, click on the wifi button, click the gear/settings icon at the top and then rename the network name/password under your primary network.