Pyret (https://www.pyret.org https://www.pyret.org) is already filling this role very nicely (browser-based Python-like for use in teaching), and has the advant

Pyret (https://www.pyret.org https://www.pyret.org) is already filling this role very nicely (browser-based Python-like for use in teaching), and has the advantage of having been designed by people whose careers are devoted to the study of programming pedagogy. It’s the language used in the front half of Data-centric Introduction to Computing, which is available online for free (https://dcic-world.org/2022-08-28/index.html https://dcic-world.org/2022-08-28/index.html). The second half of the book transitions to Python, at which point the reader/student is well-prepared to understand aspects of Python that can be tricky for first-time programmers.