Unforunately many Android and iOS apps as well are written by young programmers whom really have no backing from main stream cybersecurity professionals. This leads to these dangerous risky apps being pushed inot the wild.
VPN is a great way to protect a network but will do little to protect your personal information of data if the VPN is compromised and what's worse is, a device compromised in this manner will never warn you of the issue.
I use and personally recommend Lookout Security Personal for Android and iOS for a complete always on the job protection of my mobile devices and personal data on those devices. You can find out more at the link below: