someone in Salesforce forum provided me with the following solution: return new PageReference('/one/one.app');
It works when testing from my Salesforce sandbox, it doesn't when I do the same from my Salesforce1 sandbox. This is part of VF page custom controller, and the VF force is the core of my lightning app. The error message I get is: "You can't view this page, either because you don't have permission or because the page isn't supported on mobile devices."
Is there a way to link in Salesforce1 the feed page, a little like is it possible in Salesforce to link the home page (entry to do that is: return new PageReference('/home/home.jsp'); )
Thanks in advance for your help on this. Kind regards, Francesco