Most interesting question… Usually the challenge rather is « Tell me about Holacracy in 5 minutes » or in a few words pitch.
30 mn is an intermediate format ; too long for a pitch… and too short for a conference (45 to 60 minutes). As speaking about Holacracy to candides may be a equilibrium exercise - the more you talk, the less new people understand - I would take 5 minutes to present Holacracy through a few key points. Speaking about Gov and Tac meeting is a pretty good idea. And then I’ld ask about any questions ;-)
As people like talking, let’s them talk. About his/her job, the company, the tensions he/her senses, the big issue of the company from his/her perspective… The main idea is to make her/him trying Holacracy, instead of speaking about it. Like soccer : just kick in the ball.
Hope that helps.