To check fingerprints of all users

home-fingerprints.sh

#!/bin/bash

function fingerprints() {
  local file="${1:-$HOME/.ssh/authorized_keys}"
  echo $file
  while read l; do
    [[ -n $l && ${l###} = $l ]] && ssh-keygen -l -f /dev/stdin <<<$l
  done < "${file}"
}

for d in /home/*/ ; do
    fingerprints "$d.ssh/authorized_keys"
done