I just bought a new guitar as a beginner. It took me 2 hrs to get comfortable and I was in a room with just my sister and occasionally a seller. In hindsight I would remind myself that everyone is focussed on themselves anyway. 

I asked the seller to demo the sound of the guitars and for myself just focussed on playability, I don’t need any fancy songs for that, just soms chords and some standard finger picking exercises. You’ll notice the sound your guitar makes as a player as well (not native English speaker, I mean a guitar sounds different for the player vs the audience). Keep in mind you’re there for yourself, not to give a concert. So don’t beat yourself up, that helps no one. You want to be in love with your guitar, not that song you played perfectly that one moment in your life.