[pjmlp]

You experience is a good example why I say that Android isn't Linux, regardless how the FOSS community sees it.

Maybe for your type of work it looks different, but from app developer perspective, they could replace the kernel with something totally different, keep the constrained set of official NDK libraries and no one would notice the kernel wasn't Linux any longer.

[fla]

Even the NDK API isn't reliable. For example, some Samsung devices don't implement the complex number functions from libm.

And there is no way to know this in advance (beside checking if symbols are defined on a specific device)