As you may know, KDE has created Shashlik, an emulator that permits the installation of Android apps on Linux systems.
While Android is still Linux because they share the Linux kernel, Google’s OS has its own libraries and services while Linux uses the libraries and services brought by GNU.
So, because they share only the Kernel, Android apps do not run natively on Linux, but Shashlik provides a collection of Android systems and frameworks to ensure this compatibility.
The main problem is that such emulators do not provide 100% features of the applications and for example lack notifications. Sailfish OS, for example, is capable of running Android apps, but the experience does not compare to the one provided by the native apps.