What are some alternatives?
When comparing ReactXP and Expo Sketch, you can also consider the following products
React Navigation - Description will go into a meta tag in <head />
Native Navigation - Application and Data, Mobile, and Cross-Platform Mobile Tools
CodePush - CodePush is a cloud service that enables Cordova and React Native developers to deploy mobile app updates directly to their users' devices.
Webcodesk - A low-code rapid development tool for React Web applications
Marvel for Sketch - Sync, play and record prototypes in Sketch!