Created a Community on Reddit (/r/putonghuaxuexi/) to help people improve their Chinese pronunciation with the 普通话学习 APP. The app is great, and people should really check it out.
The APP has been updated quite a bit since I made that subreddit and resources to create an account. If there is enough of an interest on here I'll update the guide.
Direct download link to the latest version (9.8.3). Click the "普通下载" button twice to download the APK.
The subreddit has material on how to create an account, or here is a guide for version 9.4.7, together with the (now somewhat outdated) APK.
Your standards are Utopian.
I mean, provide a link to a store that has some sort of control over what's uploaded, Google Store is not perfect but at least it gives you some sense of security, I don't know if this wap.pp is a Chinese software store or not, though.