The best way to do validation on this idea would be to acquire customers through Facebook ads (rich targeting makes you able to cohort users nicely). Then, you could manually pair people via email or through a simple text messaging exchange facilitated by Twilio. In this scenario, you could prompt them to take the actions you think will be at the core of your app's functionality. Observing their engagement rate and what they do with each other would give you some insight into how viable this is.

Happy to talk this through in a call with you. I've helped a lot of clarity members through similar customer development exercises.