Oh, and Chrome itself needs to be updated -- only on what, millions of machines? V8 is bundled with Chrome -- you know, kind of like a PyInstaller app bundles Python ;-) Uhhh... no, that's kind of like how Python bundles Python. That's not
bundling an app. You update Chrome once, and every app is updated. Again, thank you for restating my point, but trying to make it sound like a counter-argument.
I would argue this sounds like a case for a "python_runner", i.e. a lightweight python vm that can run python apps, e.g. zipapps. Something like the blender_runner for blender. Making it explicitly an app that runs via some other engine.
It would then be a central entry-point that can be updated to a later python and all the apps update with it. It would have to provide a utility for desktop shortcuts to feel like the python app was launching natively.