I would say it’s also about showing people the magic of Nostr rather than telling them. The magic being  your social graph goes with you everywhere. 

What are the use cases of encouraging people to download and install a second Nostr app? 

If I am in Damus and I see an event from CoMingle that I want to RSVP to in comingle - what does that workflow look like and how do we make it simple for folks but also give them the ah ha moment? 

I don’t have the exact answer but that is the path I would pursue based on onboarding people to Nos and then Primal for zaps. You could see the light bulb go off when they logged into Primal with their nsec that they created in Nos.