You can still use the desktop site by using the 'Request Desktop Site' on your phone's browser (at least on most browsers). If you're logged in to GitHub, you can enable 'Opt out of mobile pages' in your account settings, though it sounds like you want to use both.
Best example of the above is YouTube. Have to reload like 3 times to get the real desktop site on iOS just to have background video playback and access to all videos on most pages.
(This is with YouTube set to request desktop site always in settings).