Re: Well even though my bank has an app
Fifth part one, it's far more secure than the browser - any browser. There's extra layers of security you can't have in the browser, even on the computer. The app doesn't depend on the security of other applications (like the browser, or plugins for the browser). It's sandboxed (and all others should be too) so no other applications can open it, and it can only connect to one site. It's never completely secure because you could still bypass it with (serious) user intervention, but it's far more secure than the browser.
Can you be sure of that? You say that you are an Android developer, so I assume you know something about it, but have you seen the code used by your bank's app? How confident are you that your bank has taken as much care to secure its app as (say) Google have done to secure the Android browser?
Remember that -- although it isn't actually running in the browser -- the app is using the same network stack as the browser, and may be using Android components like WebView that have a lot of code in common with the browser. That means that the app may also be susceptible to attacks that exploit the browser or networking code.
There are a lot of exploits in the code running on most Android phones because most phones don't have the latest Android versions and patches available to them. Unless you have a Nexus or Pixel phone I would be hesitant to recommend banking with a mobile however convenient it may be, and even with fully up-to-date Android you have to trust the quality of the app.