Windows has a lot of mutex and signaling primitives. Some of them can be asynchronously waited on. It also has an IoRing and I wouldn't be surprised if keyed events (the local futex equivalent) will be supported in the future.

As an aside, it is interesting that rust uses pthread_mutex for its standard library mutex. GCC/libstdc++ regrets that decision as its std::mutex is now way larger than it needs to be but it is now permanently baked in the ABI. I guess rust still doesn't guarantee ABI stability so the decision could be reversed in the future.