Is it possible to have a Python application with a GUI (such as TkInter or WxPython) with :
a Chrome browser as a widget using the main part of the GUI, displaying a certain .html page
be able to save files locally thanks to Javascript that is run in the embedded Chrome (that is normally impossible with any browser for security reasons)
If it's not possible in Python, I'm open to use another language (C++, etc.).
You mention that you're open to trying platforms other than Python. Have you seen Electron? It's a framework and runtime for building desktop applications in JavaScript with full access to the file system made by GitHub. It's based on Chromium, the same open source project that Chrome is based on.