There's quite a lot you can do here, as you can set custom functions to almost every hardware key on the device. (androidauthority.com)
Besides, some Android phones allow you to set custom functions to capacitive buttons with a long - press or double tap, which is a much more efficient use of space. (thenextweb.com)
You can change this logo with custom functions in a child theme, or using a plugin such as AG Custom Admin. (layerswp.com)