António Campos

With this plugin you can easily choose one image from your gallery and use it as logo in your wp-login.php

AC Change Login Image

This plugin changes the image in the login page (wp-login.php), you can choose any image from your gallery and use it as login logo.

UlisesFreitas

This plugin is built to work only for the <a href="https://wordpress.org/themes/storefront" rel="ugc">Storefront theme</a>.
How to use:
After installation go to Appearance => Customize => Gridder Products Gallery and change the values to fit your needs.
Notes:

Storefront Gridder

Adds a grid of products with a click and expand on the Storefront Homepage template.

AC Change Login Image vs Storefront Gridder