_COROUTINE_ABI?
The two different kinds of coroutine interfaces shouldn't be mixed and matched.
You don't gain control over any other systems.
The rules laid out.
You can put anyone you like on your guest list, even if they don't exist.
The prefix doesn't define group membership.
Just call that other thing the same way you called this thing.
You already have code execution, so it's not surprising that you can gain code execution.
It's available if you need it, but there are some tricks and pitfalls, and you may very well have better options.