That only works if there is a forever fixed version of Python embedded in your game. The value of Python in this context is its ecosystem and folks will need to install additional packages and libraries into the execution environment. Now you're managing a local distribution of Python.
Of the currently available solutions, "cloud environment made by Microsoft" doesn't sound that different from "software update made by Microsoft" in terms of how it solves the dependency hell: basically, the critical library you need is either in or out, but there is nothing you can do about it.
Admittedly, here I'm assuming Microsoft won't let you install things into the environment yourself since that basically means hosting virtual machines running arbitrary code and putting the Excel brand in front.
On versioning: we freeze the container image that your Workbook was authored against. You need to manually accept (and validate things continue to work) updates to that container image as we roll forward.