How to develop an application in react and react native at the same time?

Question

React

At the moment there is a web application that is being rewritten in react. We write our own UI kit, there is a design and everything else. The application will continue to be ported to react and eventually completely rewritten to it.
The question arose about creating a mobile application that will complement the current web application. Some features will overlap. Most likely, the mobile application will use the API that the main application uses.
The main application, quite large (5 years of development). A lot of logic both on the back and on the front, a lot of table charts, and so on. Therefore, in the future, the react-native application will develop and be supplemented with new functionality. And a lot of different functionality will intersect.
So, our team has no experience with react native, and a number of questions have arisen:
1) Do I need to create a react native application from scratch, or can we use ready-made components from our UI kit?
2) Is it possible and necessary to link these two applications somehow? (for example, to take out the logic of the components in the so-called hoc, or something like that) And make different views for two applications.
3) Perhaps someone has links to any materials (good advice) on this topic.
PS: At the moment I'm doing research on how to develop an application, collecting information, and so on.

Answer 1

If the application is rewritten to react, then the react-native-web package will help to keep the react-native + react base at the same time, but there is FlatListstill not there, they have been waiting for a long time.
For the same components - everything is simple, one file. If a different code is required for some component, you can create two files xxx.web.js and xxx.ios.js (for example), and at the assembly stage include only those that are suitable for verification (you are building for the web or for mobile).
Common components (uikit - buttons, labels, styles, etc.) - everything can be moved to a separate package / separate directory. You write what you already have - ok, use it if they are ready for this (but I think it's unlikely, you need to at least adapt / rewrite it)