It might not be possible as of now.
I am listing below what suggests it is (at least) complicated, and things you can try.
- As per this,
At the moment, you cannot type in your password right away when you
are asked for fingerprint. You need to make the fingerprint
authentication fail first (swipe wrong finger or let it time out)
before you are asked for password. This is a limitation of PAM because
its modules mustn't be threaded and hence cannot support multiple
means of authentication at the same time. (The old ThinkFinger used to
do this, but it was a gross hack which caused many troubles.) A
possible solution to this limitation is to make gdm, screensaver and
policykit-1 support multiple alternative PAM stacks.
I did not try the suggestion there (which is no more than that, a suggestion), but I found no references to anyone succeeding.
- As per this,
pam_fprintd doesn't support entering either the password or a
fingerprint, as pam_thinkfinger does, because it's a gross hack, and
could be fixed by having the login managers run 2 separate PAM stacks
Lights of hope, YMMV:
- See item 1 above.
- As per this, there is a fork https://github.com/zsxsoft/libfprint-fprintd, although it is old and not maintained.
Related:
- https://unix.stackexchange.com/questions/332149/how-to-login-with-both-password-and-fingerprint
- https://unix.stackexchange.com/questions/207360/use-multiple-pam-login-methods-at-once
- https://www.redhat.com/sysadmin/pam-authconfig ("You can set multiple options at the same time...")