I don't know which model of fingerprint reader is in the 6th gen, but on the 7th gen, enabling the beta firmware made it work perfectly.
$ fwupdmgr enable-remote lvfs-testing
If you temporarily enable, apply the Prometheus fingerprint updates then disable you won't need to worry about installing unstable firmware that will affect the system more widely.
I believe this is true. But I also have found that sometimes the user experience is diminished when not "logged in" to encourage people to create accounts. Pinterest has a box that slowly covers up more of the screen as you scroll drown. Facebook has a login prompt box that stays at the bottom of the screen and occasionally expands as a reminder. Quora prevents internal redirects to new pages. With enough know-how these can be worked around but it is an effort and I often find myself making the undesirable choice between doing the work around, ignoring the content, or signing up for an account.