Hi!
First of all great work - this works and is exactly what I'm trying to do in my app (provide a way for user to upload their own shp files).
My issue is that while I could make your example work, I did not manage to have it working on my own app. This seems to be linked to react script v5 using Webpack 5 which itself does not anymore provide a polyfill for the "buffer" Node class (used by shipjs).
While I understand this is in no way due to an error in your example, I'm curious if you did run on that problem/have any advice how to use it (downgrading react-script is not ideal onwards).