Do you want actually low res images, ie requiring generation of another image size ie not displayed and not tubmbnail?  Or do you want just a minimalistic interface?

I built a quick and dirty phone interface by just manually querying the piwigo database for the info I needed.  However, this is not the best way as I should be using the piwigo API itself such that I can avoid instances where the tables in the DB change, but so far it works for me.