If you only need your solution to work in a React Native app, then using a React Native gesture recognition library is fine.
If you want your code to be portable to the browser as well, then check out this other thread: How to enable touch input for ArcRotateCamera on Babylon React Native - #14 by ryantrem
Also, @PolygonalSun is doing more work right now to make more of the Babylon.js input system work with Babylon Native, so when that work is done it might be sufficient to simply use an ArcRotateCamera which already supports pinch zoom.