After analyzing the current scene in 2025, the verdict is clear:

Sideloaded apps do not always appear in the main "Library" tab. To find them: Go to your Apps/Library Select the filter/dropdown menu (usually set to "All"). "Unknown Sources" to see your sideloaded applications. Important Considerations

: This is a native feature that allows you to install Android application packages (APKs) directly. It does not require hacking the system's firmware.