You still need Chrome to add a key in the first place, though.
Until now, you’ve had to use Chrome to sign into your Google account with a security key. You won’t have to be quite so choosy going forward, though. Google has transitioned to using the new Web Authentication standard for hardware-based sign-ins, making your key useful in Firefox, Edge and other browsers that rely on the format. That could be particularly helpful if you want to check your Gmail on an unfamiliar PC and would rather not install Chrome or punch in a password.
There’s just one gotcha: as the key registration process still relies on the older Universal Second Factor standard, you’ll have to use Chrome to add a key to your account. It’ll “take some time” before you can rely solely on a third-party browser, Google’s Christiaan Brand said. Still, that support is at least on the way. It might not be too much longer before you can simply assume that your key will work anywhere there’s a spare port or Bluetooth connection.