Google is deploying the ability to use Google Fi via eSIM for existing iOS cellular customers, assuming that their iPhone supports it (via 9to5Google). You will need the latest version of the Google Fi iOS app and the iPhone XR, XS, XS Max, 11 series, or 2020 SE, as these phones offer dual SIM functionality. Google last month introduced eSIM support to existing Google Fi customers.

Although the release notes for the Google Fi iOS update yesterday say that "you can now activate Fi on select iPhone devices via eSIM," some Google Fi users on Reddit have had to uninstall their Google Fi app and follow the instructions on the Google Fi website to add a cellular plan to their iPhone to get eSIM to work. Google has not responded to a request for comments as to when eSIM might be rolled out more broadly to current Google Fi customers on iOS.