https://techcrunch.com/2018/05/30/google-fi-adds-support-for-the-moto-g6-lgs-g7-and-v35-phones/

Project Fi, Google’s wireless service, is getting support for a number of new phones today. Until now, if you wanted to switch to Fi, the only officially supported phones were Google’s own Pixel and Pixel 2 phones, the Nexus 5X and 6P, as well as the Moto X4 and its Android One variant. Today, Google is adding the Moto G6, as well as LG’s G7 ThinQ and V35 ThinQ phones to this list.

Since Google’s network is a bit different from its competitors, thanks to Fi’s ability to switch between the networks of T-Mobile, Sprint and U.S. Cellular to provide users access to the strongest signal in a given area, the company has always taken a very strict approach as to which phones it officially supported.