Wow, the PWA is really impressive. Honestly it's starting to get hard to tell the difference between this and Electron-based editors like VS Code. I'm really excited for integration with the File System Access API; that's the final puzzle piece I'd need to use something like this for serious work.
Since Electron is just chromium, I'm not sure why you would expect a difference in the first place? The differences that previously existed between Electron & Web hasn't changed - Electron's only real purpose was to basically turn off the browser permission model & let the "web app" do whatever it wants. That's still true with WebContainers, it still has its hands & features tied to whatever Chrome & browsers in general are comfortable letting websites ask permission to do.