@Henry_Luengas Thanks so much for the guide! I am using Linux Mint 20.2 with Cinnamon. A couple of notes for anyone else doing the same:
sudo apt build-dep doesn’t work, but the build process will tell you which dependencies are missing. Manually install them with sudo apt install. debhelper-compat does not exist because it is provided by debhelper. After you’ve installed all the other dependencies, as well as making the other necessary modifications in the guide, append -d to the build command to force it to ignore the lack of debhelper-compat.
apt-source --download-only fprintd fails to locate a source package. Use curl -O http://ftp.debian.org/debian/pool/main/f/fprintd/fprintd_1.90.9-1.debian.tar.xz instead.
The Cinnamon user configuration doesn’t have fingerprint configuration in the GUI, but you can configure it from the CLI.
fprintd-enroll -f right-thumb (or right/left index,middle,ring,little finger). Note that it will take many passes to complete, so don’t worry when you see a lot of remove-and-retry messages.
Then
sudo pam-auth-update and ensure that the Fingerprint option is selected.