Have you a) looked through linkedin to see who are the UX engineers at GitHub, b) found their blogs / twitter profiles to see what they write about / what the r

Have you a) looked through linkedin to see who are the UX engineers at GitHub, b) found their blogs / twitter profiles to see what they write about / what the read, c) read their writings, d) read what they are reading, e) reached out to a few of them to get their advice? It seems to me that you've done just about everything other than talk to the actual people who have what you want. So at this point, go for it! Find them, talk to them, ask them what you need to do, and then do it. :) Good luck!