You can already do that.
The thing is that there is nothing to do in HikaShop for that. Instead that's something to handle with your joomla template. You should either have two templates, one for normal computers, and one for mobile devices (and then redirect to one or the other with a plugin
extensions.joomla.org/extensions/mobile
), or you could directly have a template which handle both (the joomla templates based on the T3 framework or the gantry framework can do that).
