W3C proposed the use of Web Authentication APIs back in January, following which companies started working on implementing APIs to allow users to use physical keys to log in on websites and apps. Now, Mozilla is planning to take it one step further by adding support for Windows Hello to Firefox.
The company disclosed the news on their website which also states that the implementation of Windows Hello is a priority for the company.
WebAuthn no longer works on Windows Insider builds, as compatible security keys are no longer available via the USB HID interface. (Basically, u2f-hid-rs  will stop supporting Windows 10+). Sometime this spring, Firefox 66 or 67 (and ESR 60) will need to use the Windows Hello API on when available to interact with Web Authentication. Otherwise, no devices will be detected and we’ll have a Windows feature regression. The relevant API headers are provided by Microsoft as MIT-licensed files  as they will need to be checked into mozilla-central.
– J.C. Jones
Firefox has set the deadline for implementation as the spring of 2019 which is not far. With the availability of Windows Hello, users can finally log on websites and use apps without typing the password.