I will agree - async rust on an operating system isn’t all that impressive - it’s a lot easier to just have well defined tasks and manually spawn threads to do the work.
However, in embedded rust async functions are amazing! Combine it with a scheduler like rtic or embassy, and now hardware abstractions are completely taken care of. Serial port? Just two layers of abstraction and you have a DMA system that shoves bytes out UART as fast as you can create them. And your terminal thread will only occupy as much time as it needs to generate the bytes and spit them out, no spin locking or waiting for a status register to report ready.