I'm looking for people to test an app for community coordination. Where should I start?

I have been working on an app that is supposed to help groups of people coordinate their actions towards a shared goal. I'm done with the basic features (I'm talking barebones here) and I am trying to find a community or two that would be willing to work with me to test and improve it. The reason I'm asking here is two-fold:

A) When I looked up ways to find beta testers most are based on finding individuals to test the app which doesn't really work for this because it is based on helping a pre-established community. So I am stuck on how I would find communities without already being an established app.

B) Lemmy seems like a very passionate/driven community so I thought there would be people here that are working on stuff or at least know places I could ask for help on this.

So what would be the best thing for me to do?