Take The Google Pill
"On Wednesday, Google is addressing this last drawback with a new method that brings Android keys to iPhone and iPad users. It relies on the Google Smart Lock app running on the iOS device that communicates over Bluetooth with the built-in key stored on the user’s Android phone or tablet. (The app, which is also used to make FIDO-based crypto keys work with iOS devices, has user ratings of just 2.2 out of 5.) Google has additional instructions here. Company representatives declined to provide interviews for this post." - via Dan Goodin, writing at Ars Technica