Many modern apps no longer support Android 5.1. Users may find that the Play Store works, but specific apps (like banking or high-end games) will not install due to the old API level.
This era gave rise to various distributions of GApps, such as "PA GApps" (Paranoid Android) and "Banks GApps." Enthusiasts debated which package was superior—opting for "Micro" packages to save space or "Full" packages to get every Google feature. This highlights a unique aspect of the Android philosophy: the separation of platform and services. Unlike iOS or Windows Phone of that era, Android 5.1 allowed users the choice to run a pure Google experience, a de-Googled AOSP experience, or a hybrid of the two. gapps android 51