Cosmopolitan binaries aren't interpreted. They're just flat x86 binaries. It needs a 12kb runtime that's written in C. All the runtime does is (a) polyfills magic numbers for the SYSCALL instruction and (b) boot-load from BIOS to long mode on metal w/ linux kernel style negative memory page tables. So basically, it's just glue that takes care of the ugly low-level system details so you can bolt on whatever high level language interpreter you want. For example, the Wasm3 engine recently adopted it.