Android is a Java based OS, which happens to use Linux as kernel, Google can very easily change it to something else.
Only these set of C and C++ libraries are available to native applications on Android, which happen to be compiled to a .so anyway, to be loaded inside ART/Dalvik.
Trying to link into any other GNU/Linux library that happens to be on the devices, but isn't part of that list, will trigger an app termination, starting with Android 7.
It has the Linux kernel you just bring the GNU or whatever you need. But Google now supports containers on ChromeOS so if access you can just run in a container and the use Android X Windows server on same box.
If Google would gives this away have my perfect development solution. I can play my Android games on my 2 in 1 and then use full Linux when in laptop mode. But I can also debug my containers on my laptop as native.
But when needed I have sold browser and other core things can never be touched. Basically give me a iPad and a Chromebook and a full Linux development machine. Well no kernel dev on Linux but most things, native, shared read, etc.
But I want an extra SSD that is separate from the kernel SSD. I think this can be done and even keep read share from boot dev and something running as a container.
Correct, Android is not GNU/Linux, I responded too fast.
As the parent comment spoke about DirectX support, I should have phrased it 'Android is also in the camp of "Doesn't support DirectX" and counts for a large number of devices.'