So? There is instrumentation for Async Rust being added. Just not in the Rust compiler and not in tokio. More in application level code. So as far as the user is concerned to "their" Rust run-time. A distinction that is mostly useless when programming lisp. Hence lisp.

Lisp is about solving your problem and getting the "language" out of the way. So you add what is missing. As long as it works it doesn’t even matter where it’s added.

Even C has a barebones runtime environment when compiled for a machine with an MMU and an OS, so not a microcontroller.