I am working on some tools that needed to be able to insert & extract data from a closed web app. I wrote an extension and local server that has SSE APIs that allow the tool (native code app) and a chrome extension that can also talk to the local server via SSE / event sink and provide to the native app a pseudo “open” API. Works really well, the web app that it talks to has no idea it’s not a human pushing and pulling data. To be more clear, the server is embedded inside the native app.