It seems to be possible to use hyper with async-std if you provide a Connector for it that uses async-std. Considering half the ecosystem is seemingly moving to async-std and tokio doesn't play well with async-std, there should probably be a good rustls based Connector that can be used in that case. I'm not sure if that is within the scope of hyper-rustls or if we need a second hyper-rustls-async-std.