I mostly agree with @timfelgentreff. From the PyPy point of view these small (and seemingly inconsequential) differences in behavior tend to be feasible, but often end up being somewhat annoying to follow because someone somewhere always ends up relying on every last precise detail. Therefore, the fewer behavioral quirks introduced by such a change, the better.
(Sidenote, GraalPy is pretty clearly the most well-resourced alternative Python from-scratch implementations at the moment.)