I have checked react-native registry and found following https://www.npmjs.com/package/react-native-file-viewer/v/2.0.2 or https://www.npmjs.com/package/react-native-fs
The problem remains how to incorporate this module to Mendix. You can try with following guide on https://docs.mendix.com/howto/extensibility/build-native-widget
I hope it helps you.
Just found a new widget in the appstore- Native file documents ( https://appstore.home.mendix.com/link/app/114252/)
This can access the file system of the native device.
A sample project is also available – Native file documents sample project(https://appstore.home.mendix.com/link/app/114253/)
Note- this only work on custom build.