The purpose of this forked version is that it will work as a gateway between Android Windows Phone devices, Nokia has redesign UI of this Nokia X in this way that you will find it very much similar to of WP UI and if later you want to upgrade then you can easily switch to WP devices like Lumia series.
If you want to know and discover a little about Nokia App store then here is an apk for you which lets you download and install Nokia App store on any Android device.
Before you install it, first go ti Settings > Security and check the Unknown sources so that we can install this apk file.
Once you did this, you can download APK file from HERE, now using your favorite file manager navigate to your download location and install it, once installation has been finished you will find an icon on your device, tap on it and start browsing.
As its straight ported apk you might find some bugs, it wont have much apps but you can browse it and see how it looks and what features it has at this time.