Is it possible to try react native code without computer?

Answer 1

It's possible.
Write code on mobile from https://snack.expo.io/
Test it on expo app.

Answer 2

You are right, snack expo is one of the solutions.
I have found an android app in Play Store called react-native-Playground

Answer 3

https://stackoverflow.com/questions/48152008/can-you-use-react-native-to-create-a-desktop-app

See this post