According to stubtest, these exist on all platforms, not just Linux

Ok, here's what is going on:

>>> import sys
>>> sys.activate_stack_trampoline('perf')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: perf trampoline not available

Source: https://github.com/python/cpython/blob/3.12/Python/sysmodule.c#L2166-L2168

I think that I can add a def activate_stack_trampoline(__backend: str) -> NoReturn for non-linux versions.

I'd actually be okay with keeping the sys.version_info branch and adding allowlist entries on Windows/Darwin in that case! (We should add comments to the allowlist saying why they're not included, though).

I think that adding it is better, users might do something like:

try:
   sys.activate_stack_trampoline('perf')
except ValueError:
   some_other_case()

And it is quite easy to do with conditional definition.

Yeah, makes sense!