There are projects like emscripten that can compile C/C++ source into JS, and therefore port CPython to JS, but there’s more to software than just the language itself, and you would actually have to set up browser alternatives of OS services, typically used by native code.
It’s by no means trivial, but it can be done, and I can do it, for $60,000.
So, go get the money, and you’ll have “web publishing”.
However, it’s not going to help most people here, because they are not capable of making anything that anyone anywhere would actually be willing to spend time and play, let alone pay for the privilege.
But hey, if you can get the money together, I’ll be more than happy to take it.