Just report them for copyright infringement. Apple will take the blatant cases down. The copy-cats that don't infringe are just a side effect of success, so... congrats?

Regarding Reddit, it's a great place to find users but also copy-cats. Stick to posting "I built a thing that solves a problem" and avoid the bragging "I made $N in N days" indie-hacker style. The latter doesn't help the app anyways.

Moat: there isn't one for a utility someone can build in a few days. It can still be a good business - you seem to have marketing savvy which is a big part of it.

One suggestion, on your homepage - the "See USB Connection Information in Action" the screenshots are much too small. Nice looking app!