[AdelaideSimone]

What exactly is it you're "right" about? How do you think any libc wrapper or direct syscall works? Syscalls are filtered for security reasons on many platforms, including Android. I mean, a syscall is literally an API itself to get a kernel's internals to do something for you.

What you're suggesting is, as someone else said, non-sensical. Phrased without invincible ignorance, it's equivalent to saying, "Android prevents you from creating a new OS kernel to supplant its own control over hardware access," which is true of basically any OS. How helpful or secure would it be if you could make 0 guarantees about how your hardware is used?

You can do direct hardware access through drivers that are integrated/interfaced with the kernel somehow, but this still is not an entirely arbitrary access, and is still going through the kernel in a way.