I'm interested in this too - ideally I want to force the mobile site to show on a tablet when portrait, instead of the desktop version, however after looking into it it doesn't appear there is an easy fix.
Is it a case of adding custom code per page, or do you need to do per item? If per page, it might be doable, too complex if more than that for me. Unfortunately on the site I'm currently working on I can't share the link due to confidentiality but would be good to understand how it might work.
Thanks in advance.