BlackBerry OS 10 brought us the ability to sideload Android apps on BlackBerry 10 devices, but the issues with sideloading can be numerous to nothing depending on the nature of the app being sideloaded.
If you are having trouble running an Android app on your BlackBerry, or you have had the experience where some functions in an Android app is not properly supported in the Android player, then you should go upgrade to the BlackBerry OS 10.1.2 This version of the OS allows direct installation of Android apps to your BlackBerry, and no the apps are not available in App World.
To install an Android app directly to your BB device, you will have to find and download the APK file for the app you need.
After your download has completed, click on the file to open the install prompt, then choose install to start the direct installation of the APK file. After installation is complete, choose Open, then witness the Andoid app run on your BlackBerry phone without the trouble of sideloading.