Is PySide6 the best framework to completely replace Electron for heavy desktop apps, or should I learn something else?

I am building a custom asynchronous engine ("Storm Core") in Python to handle massive file operations and multi-agent AI tasks without blocking the UI.

Yesterday, I connected my file browser directly to this core and tested it on my Desktop directory (31.2 GB, 113,000 files, 16,000 folders). Because of the async architecture, it loaded in milliseconds without a single UI freeze.

I am currently using PySide6 for the frontend .

My ultimate goal is to completely move away from Electron and build blazing-fast, beautiful applications 100% in Python. Since I am self-taught, I have an architectural question for the community before I lock myself into this stack:

1. Is PySide6 the absolute best choice for high-performance, modern-looking GUIs in Python?
2. Are there other Python frameworks I should look into that handle asynchronous data streams better or offer more modern styling capabilities?
3. What do experienced developers use when they need to build an "Electron-killer" purely in Python?

I want to make sure I am investing my time in learning the right tools. Any advice on GUI frameworks is highly appreciated!