Embassy is a single threaded RTOS. Moss implements support for Linux ABI which presumes the existence of threads. The fact that async/await doesn’t itself imply anything about threads doesn’t negate that using it within the context of a kernel implementation of the Linux kernel ABI does require thread suspension by definition - the CPU needs to stop running the current thread (or process) and start executing the next thread if there’s any blocking that’s required. Clue: there’s a scheduler within the implementation which means there’s more than 1 thread on the system.

You’re arguing about the technical definition of async/await while completely ignoring what it means to write a kernel.