Google’s website lists a handful of Samsung phones that they claim are designed for their Fi network and will support 5G. They also note that “Phones compatible with T-Mobile’s 5G network will work with Fi’s 5G network”, which seems to imply that the iPhone 12 should have no issues connecting to 5G.
However, iPhone 12 customers discovered that when it came to their iPhone’s settings, they could not select 5G and were still limited to LTE. Google has since confirmed to 9to5Google that 5G support for the iPhone 12 is not available, but they will keep customers updated. “Right now Fi 5G is not supported on iPhone 12 series; we’ll keep customers updated on the latest via our help center.”
It seems a bit strange that iPhone 12 users can’t hook onto Google Fi’s 5G despite the fact that Google Fi is an MVNO that essentially piggybacks off the likes of T-Mobile and Sprint, but for now it looks like iPhone 12 users will just have to deal with it until Google flips the switch.