I have a pair of Google Titan security keys and want to configure ubuntu 18.04 to accept them for login. The instructions for a Yubikey here work well for USB. I haven't found a recipe yet to use the bluetooth connection to the Titan key on ubuntu. Any suggestions on how to do that would be welcome.
I had the same desire, found that the BLE key is only intended for use with Android or iOS devices over Bluetooth at this time. The key will work when hard connected.
More information at https://support.google.com/titansecuritykey/answer/9115487?hl=en.