Rails + Stimulas or Rails API + React

Hi Chris

I have worked on many Apps with different set of architectures but never find this case at inceptive period that which approach we might choose to scale our Rails app either from being a server rendered app to become an API app and support Client Frameworks or make a Rails API backend that can serve Web and Mobile Front End both.

I have two scenrios to outline my Question:

1. (Confusion) that to do a fast pace development of your startup, you can go ahead with Rails + (Our New Stimulas). But what if you feel, later or at initial level, that you might need to support your app on mobile platforms. What would the best way to start your project with?
2. Even if I don't have to think too far ahead because trying to optimize for the later state has the potential to slow down the initial development and that's is for sure. Then, as a Rails Engineer, how facile it would be to get a Mobile app?