Yup. You can basically write your own language with different syntax and get python to treat it like any other python code. Hy is a language which works this way: https://github.com/hylang/hy (see this part of their documentation for how the user can use this: https://docs.hylang.org/en/master/language/interop.html#usin...)

I think goto has been implemented in a few different ways in python. Here's another example which abuses existing syntax and edits the bytecode of the function after its compiled: https://pypi.org/project/goto-statement/