If you don't need a server then React Native should basically be your entire stack. :)
Since you do probably need a server, I don't have an incredibly educated answer for you but I use Node + Mongo on AWS because it's cheap, easy, entirely JS, and seems like it'll scale reasonably well (to some point).
It's really up to you. It's a tradeoff between spending additional effort on dev ops now (rather than product) versus building the technical debt that will be converting your app over later. If everyone on your team knows Redux then sure, start the app's architecture to scale to a huge team. If it'll significantly slow down product development then have everyone learn + convert later.
I'd err on the side of the latter (vanilla RN, Redux when you need it) to move fast on your product.
