It&#x27;s pretty simple: almost all efforts to duplicate POSIX in a safe language failed. The commercial practice is porting a POSIX or Linux API in C to a virtualized partition that runs on microkernel. Safety-critical apps run either directly on the microkernel or on a minimal, language-specific runtime running directly on kernel. Keeps TCB tiny. Overall app&#x2F;system is split with untrusted components in POSIX&#x2F;Linux system &amp; security-critical stuff in the minimal partitions. Unlike safe POSIX, this is a proven model done by many small teams.<p>In this case, it would be a RTOS or user-mode Linux, plus a custom runtime or target for Rust apps, and IPC&#x2F;middleware to connect the two. Way easier to build. POSIX comes later if effort comes along.