15% of the consumers is, I'm guessing, based on US marketshare?

The company in the OP here is not American, and outside of the US, Android has the majority of the smartphone marketshare in most of the world.

Despite what Americans often think this is not only true for "poor countries" either. In the UK it is pretty much 50/50 between iOS and Android. Most people have either an iPhone or Samsung. Usually the flagship models.

So there's very good reasons to target Android and it is very possible OP's company is simply in a country where Android smartphones dominate the market, not iPhones.

But yes regarding the Epic thing, you can indeed submit your apps to third party app stores including ones that come preinstalled on the major brands. Samsung Galaxy Store for example.