Have a look at the plugin "Msg footer".
You can put Html in the "Banner/Logo"
I am using a modified buglink plugin to link to a webpage "Impressum".
util/add_theme_repo [zrl=https://github.com/ansorg/hubzilla-themes-ja.git]https://github.com/ansorg/hubzilla-themes-ja.git[/zrl] htja
There used to be a static page footer region and plugins to make use of it; but then we started doing endless scroll and we had to deprecate it. These aren't very compatible.