I agree with you on the Universal API. But It cannot cover any case, unfortunately. But the micro-kernel can help here by translating the NxM problem to N+M by

I agree with you on the Universal API. But It cannot cover any case, unfortunately. But the micro-kernel can help here by translating the NxM problem to N+M by reusing device servers, which can have a universal API and can be written in any native or not programming language. Now, you can virtualize your OS over the microkernel and re-use the servers. That was the initial dream.