> Would you use this app if I built it

No, because of the gamification angle:

> The app will encourage you to invite friends to form teams. The teams will drive leaderboards, gamification and hopefully some virality.

I wouldn’t want yet another app trying to manipulate my behaviour[1], even if for an ostensibly good reason[2]. I’m unsure if competing around “which team does the most good” is a healthy way to solve the problem.

But I applaud your cause and might reference the app’s existence to some people on that basis. Whether I’d do that or not would depend on the implementation.

[1]: Though I appreciate your honesty.

[2]: What happens if incentives shift?