I think a better question is what do *you* think would happen if one were to stick a Commodore 64 ROM into an Apple II. The answer is essentially the same as what you could reasonably expect from plopping a Newton ROM onto a cell phone, after all. Would every issue you encountered doing this be a "second order problem"? What level of technical skill do you believe would be required to work around these problems? What tools and documentation would you need to fix them, and would such fixes be trivial in nature or would they entail partial or complete rewrites of the hardware drivers and OS kernel?

Honestly I'm genuinely curious how much you know about the Newton OS (or operating systems in general) at a low level, given your apparent confidence.