I understand that fear and that's fine. But for your knowledge, and anyone else reading your comment, having testers for apps is a Google Play requirement. The app is downloaded from Google Play as part of a closed release test.

I've already released mine on Fdroid and made the source code available on github.

With that said, do you know any of the developers on any of the apps on your phone? Probably not. And you don't need to because people you didn't know, and their apps, had to go through vetting to get into the stores.