> Add to that, you need to support like ten thousand devices, many of which are running Android 4.4 (which, IIRC, is like three years old) and have a WIDE range of screen sizes.

I've been developing Android apps for years (before support lib even existed, much less all the fancy new kids) and range of screen sizes has literally never once been an actual issue. Use 'dp' instead of 'px' and you pretty much never have a screen diversity problem. All the platform views & layouts handle the majority of the work.

Does React Native make this more complicated for some reason?