I've used C++ coroutines (with io_uring). They are really useful in this case and allows one to write code like one would with the simple blocking API. And from what I've read they are better than Rusts coroutines for this use case (and for the yield use case they aren't good).

It adds an additional foot-gun w.r.t. to e.g. by-reference parameters to functions and their lifetime. The function parameter might not be alive anymore after a "co_await" and it doesn't require any capture (like lambda) or has any hint about this being the case.

Then, the tooling isn't there yet (other than the missing standard library). Gdb doesn't show correct lines and can't print local variables when in coroutines. If there is a deadlock one can't see the suspended coroutine (and its call stack) holding the lock, etc.. Back to printf debugging...