Indeed, Python is one of the most well behaved scripting languages for WebAssembly, and people were running in browser for a good while already with WebAsembly predecessors (emscripten and asm.js).
With https://github.com/pybind/pybind11 there is really great integration with C++ and Python is my second home after C++ actually.
Anyway, I am quite happy with Wren and it seems to be fast (not a requirement for my project, though)