It would need to be as simple as possible since you’re doing it in person. Doubt they will stand around going through a bunch of steps. Honestly, we have apps like Damus and amethyst that already have decent onboarding, and snort is super easy to sign up on. 

You could recommend one, have them sign up and scan your qr.

Just feels like a lot of extra work on your part for not much gain. Much more interesting things to work on.