We have discussed Google Fi a few times on this forum. My verdict is that it’s not a suitable service for digital nomads, perpetual travelers or those that aren’t in the US often. There have been many cases where people traveling abroad (even American residents) for an extended period have had their accounts suspended.
Their TOS is quite clear:
The Services are offered only to residents of the United States. The Services must be primarily used in the United States and are not intended for extended international use. Further, the Services are designed for use predominantly within our network. If your usage outside our network is excessive, abnormally high, or cause us to incur too much cost, we may, at our option and sole discretion, suspend your Google Fi account, terminate your service, or limit your use of roaming.
Here are two topics with more details about Google-Fi: