MicroPython's a bytecode interpreter so, other than the existing Python ecosystem being a huge boon (popularity being a form of strength), you could get many of the same benefits and more from wasm

If we forget about the pain that most WASM toolchains happen to be.

MicroPython, like most BASIC interpreters in 8 bit days, also allows for inline Assembly.

As for running bytecode on MCU that is as old as MCU themselves, wasm doesn't bring anything to table.

https://en.wikipedia.org/wiki/BASIC_Stamp

You can actually opt-in to native compilation on a function level so it's not just a bytecode interpreter. You can also compile it yourself with additional functionality written in C/C++ and just use Python for the glue that isn't performance sensitive.