Country List w React, Redux, React-Router and grid

I am very proud of this one. I think it works and looks good. The first thing I'm a bit concerned about is first loading time. I'm downloading the whole JSON to store it on Redux. That is causing some loading time, especially on mobile. Don't know what to do about it.

Another thing is about accessibility. I'm using my own component instead of a select input. Right now, it doesn't support tab Index and I don't know how much more problems I have in terms of accessibility. What can I do to improve it?

Thank you all for checking!